The Scale Penalty
As an agency adds people, the share of every dollar it actually keeps as profit tends to shrink.

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The mechanism
Four bars show the profit kept after tax at different sizes. The smallest studio, under 10 people, keeps the most at 19%, and each larger size keeps less - 12%, then 9%, down to 8% for firms of 50 or more. Getting bigger adds cost, like more staff and more overhead, faster than it adds the power to charge more. So growing your headcount can leave you keeping a thinner slice of each dollar.
Part of Persistence. Infrastructure that keeps growth compounding past founder heroics.