The $2k number isn't the issue here. It's just a number, if you disagree with it replace with with something else. The point is that the author argues there's a

The $2k number isn't the issue here. It's just a number, if you disagree with it replace with with something else. The point is that the author argues there's a ceiling to agency earnings. That being said, the article is wrong because of other, more fundamental reasons. The first point essentially argues that churn goes up as the client list grows (because it's a constant percentage), so at some point the new incoming clients will be the same as the ones churning so the agency will be at sales equilibrium. This relies on assuming that the rate of new clients is constant. I would expect agencies to get better at client acquisition as their reputation and experience grows. So you'd have to show that this growth rate is slower than churn rate at some point which isn't obvious/proven here. The second point states that the owner runs out of attention with too many clients regardless of how many talented employee they hire. This, however, explicitly assumes that owner spends an equal amount of time between each client. A wiser strategy is for owner to concentrate their energy on high-value deliverables and touchy client relations and farm the common/generic work to employees. The math just makes bad assumptions.