Salary
Average Salary: $65,000
Expected Lifetime Earnings: $2,600,000
Small. Most entrepreneurs make next to nothing, or at least take very small cash salaries—just enough to feed them, pay for a cheap apartment, and a car that (usually) works (source).
For many who made it to The Club (of billionaires), they'll tell you that their best days were being poor and spending twenty hours a day (four sleeping) at the office. The culture is all about living cheaply and having everything "on the come" so that if your company ends up being worthy of going public or selling for a big number, your equity value is ginormous and the rest then is literally history.
Of course, if you are the one who comes up with the next Facebook, then there's really no limit to how many boatloads of money you can make. Yes, you can go ahead and write "boatloads" right there on your tax return.