A product can have the fit that the retention article described, and be built well under the constraints the execution article set out, and still fail. It fails when the people who would keep it cannot be reached at a price worth paying, or when those reached are charged less than they cost to win and to serve. This article is about that last stretch, distribution, the work of reaching customers, and getting paid, the work of charging them enough. The two together decide whether a product with fit is also a business, and they decide it through an arithmetic that can be written plainly. The treatment is general, and it is information rather than business advice.

A Brief History

The oldest mistake in the subject is the belief that a good product sells itself, that if it is built they will come. They do not come, or not in the numbers or at the cost required, and the correction is associated most sharply with Peter Thiel, who argued that poor sales and distribution, rather than a poor product, are the more common cause of failure, and that founders systematically neglect the question because building is visible work and selling feels beneath the engineer. A parallel literature on traction cataloged the limited set of channels through which customers can actually be reached, and urged a deliberate search among them rather than a hopeful default to one. Alongside this, the software-as-a-service era made the underlying accounting precise, giving the discipline of unit economics, the lifetime value of a customer weighed against the cost to acquire one, and the time to earn that cost back, which is the arithmetic this article develops.

Distribution Is a Gate

Distribution is a stage of the funnel, not a thing that happens after the real work. The channels that reach customers are few, search, advertising, sales teams, content, partnerships, marketplaces, and word of mouth, and each has a cost and a ceiling. A founder who has not chosen a channel deliberately, and measured what it costs to win a customer through it, has not yet learned whether the product can be sold, only that it can be built. The one channel that does carry a product by itself is the word of mouth of satisfied users, and that channel is a dividend of fit rather than a substitute for distribution, which is why it is treated last and not first. Reaching the wrong people cheaply is no better than failing to reach the right ones, since only the customers who keep using and keep paying, the right people of product-market fit, repay the cost of acquisition.

What a Customer Is Worth

A paying customer yields a contribution margin each period, the revenue they bring less the variable cost of serving them, written $m$. The customer churns at a rate $c$, the same churn the retention article wrote as $\lambda$, and so lasts on average $1 / c$ periods. The undiscounted worth of the customer is the margin times that lifetime, $m \cdot (1/c) = m/c$. Money arriving later is worth less than money now, so discounting the stream at a rate $r$ per period gives the present value

\[V = \frac{m}{c + r},\]

which is the discounted area under the very retention curve the earlier article integrated. Take a margin of twenty dollars a month, a churn of five percent, so an average life of twenty months, and a discount rate of one percent a month. The undiscounted worth is four hundred dollars, and the discounted worth is about three hundred and thirty-three, the difference being the price of waiting.

What a Customer Costs

The cost to acquire a customer is the total spent winning them, the sales and marketing outlay divided by the customers it produced, written $A$. The first condition of a business is that a customer be worth more than they cost,

\[V > A,\]

but mere positivity is too weak a test, since overhead, failed experiments, and the rising cost of later customers all consume the gap. A common standard of health asks for a wide margin,

\[\frac{V}{A} \gtrsim 3,\]

a customer worth at least three times the cost of winning them. A prior condition is easy to forget, that the per-period margin must itself be positive, $m > 0$, because a venture that loses money on each sale does not make it up in volume. It only loses faster. At an acquisition cost of one hundred dollars, the worth of three hundred and thirty-three gives a ratio above three, a healthy business, while at three hundred dollars to acquire the ratio falls near one, a venture spending almost as much to win a customer as the customer will ever return.

Payback and Runway

The ratio says whether a customer pays off. A second number says how soon. The payback period is the time to recover the acquisition cost from the margin the customer pays,

\[t_{\text{payback}} = \frac{A}{m}.\]

At one hundred dollars to acquire and twenty a month in margin, the cost is recovered in five months, comfortably inside the twenty-month life. A payback longer than the lifetime is a loss disguised as a sale, since the customer leaves before repaying. Payback also governs growth. A venture that recovers its acquisition cost quickly can spend the returned money to acquire again, so that a given runway, in the sense of the execution article, funds far more growth when payback is short than when the cash is tied up for years.

Why Channels Saturate

The cost to acquire a customer is not a constant. The cheapest customers in a channel are won first, and as the channel is pushed harder the marginal cost of the next customer rises. Acquisition adds value only while the cost of the next customer stays below their worth, $A_{\text{marginal}} < V$, and the channel reaches its ceiling where the two are equal, beyond which each further customer destroys value rather than creating it. This rising marginal cost is why a blended average flatters a venture that is scaling, and why no single channel carries a business forever. Growth past one channel’s ceiling requires finding another, which is the deliberate search for channels that the traction literature urged.

The Cheapest Channel

The least costly channel is the product recruiting for itself. When satisfied users bring others, the new customers each customer brings is the viral coefficient $k = i \cdot q$, the number of invitations a user sends times the fraction that convert. One acquired customer then begins a chain, themselves, then their $k$ recruits, then those recruits’ $k$ each, summing while $k < 1$ to

\[1 + k + k^2 + \cdots = \frac{1}{1 - k}.\]

Each paid customer thus brings $1 / (1 - k)$ in total, and the effective cost of acquisition falls to

\[A_{\text{eff}} = A\,(1 - k).\]

At a coefficient of one half the cost halves, and at four fifths it falls to a fifth. The effect on viability is direct, since dividing the worth by this lower cost

\[\frac{V}{A_{\text{eff}}} = \frac{1}{1 - k} \cdot \frac{V}{A}\]

multiplies the health ratio by the same factor. A venture paying two hundred dollars to acquire a customer worth three hundred and thirty-three, a ratio of about one and two-thirds and unviable on paid acquisition alone, reaches a healthy three and a third at a coefficient of one half, rescued not by spending less but by being worth talking about. When $k$ reaches one, the chain no longer converges, growth sustains itself, and paid acquisition becomes a choice rather than a necessity. A high coefficient is a dividend of the fit the earlier article measured, since only a product people genuinely want is one they tell others about, which is the sense in which distribution and fit are not separate problems.

Getting Paid

Reaching customers is half the stretch. Charging them is the other. A price must clear two bars, sitting above the cost to serve, so that the margin $m$ is positive, and below the value the customer receives, so that buying remains worth their while. The room between those bars is where a business lives, and a product that delivers great value but captures none of it in price is a gift, not a company. Users who will never pay, however numerous, are not customers, and counting them as traction is a form of the vanity metric the retention article warned against. Everything in this article rests on the margin $m$, which exists only when someone is charged more than they cost. Distribution decides whether they can be reached. Pricing decides whether reaching them pays.

Epistemic State

The quantities here are estimates, and softer ones than the symbols suggest. Churn, margin, and acquisition cost all drift over time and differ across customer segments, so a single lifetime value averages over a population that is not uniform. The acquisition cost in particular rises with scale, which means a healthy ratio measured small can decay as a venture grows, and a blended average can conceal a marginal cost already past the ceiling. The threshold of three is a convention drawn from experience, not a theorem, and the discount rate is a judgment. The viral coefficient is rarely stable, since it decays as easy adopters are used up, and a coefficient above one is rare and seldom lasting. What survives these cautions is the structure, that a customer must be worth more than they cost, by a margin and within a time, and that the cost is not fixed but climbs as channels saturate. Throughout, this is general information, and it is not business advice.

Out of Scope

The tactics of particular channels, search optimization, advertising auctions, sales-team design, and content strategy, are practical crafts left to their own literatures. The depth of pricing strategy, segmentation, discrimination, and packaging, is a large adjacent subject touched only at its principle here. The accounting conventions that define acquisition cost and margin precisely are matters for the finance function. The durable advantage that a cheap and defensible channel can become belongs to the final article, which asks what makes the whole construction last.

Conclusion

A product with fit becomes a business only when the people who want it can be reached affordably and charged enough. The customer must be worth more than they cost, $V > A$, by a wide margin and recovered in a time shorter than the customer stays. The cost is not fixed, but rises as each channel saturates, so growth is a search across channels, and the cheapest channel of all, the word of mouth of users who genuinely care, is earned by the fit of the retention article rather than bought. The funnel placed distribution and revenue among the stages that gate survival, and this article gave them their arithmetic. The final article asks the question that remains once a venture can build, hold, reach, and charge, namely what keeps a rival from doing the same, and where durable advantage comes from.

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