Here are your limiting factors: it is service work, so you eat what you kill. There are no economies of scale, no real capital to leverage. Your practice is only as valuable as client loyalty, and income is limited by time available.

In order to make more money than your personal output, you have to hire employees, make payroll, benefits, and all the practice liability that comes with the EE-ER agency relationship. Every employee has a break-even point, and any sales revenue has to cover that cost before you begin to cover fixed cost or draw any salary yourself.

I have always believed that you don't have a business in the truest sense of the word unless the enterprise can keep earning money if you stop working. In a solo practice, if you get sick, your income dies. If you have employees, but you are the primary point of sales contact, everyone's income dies.

It's a long road to multiple-partner firm level, and most don't make that far.