When the tax code was 90%, the effective tax rate was 10-15%. You clearly aren't informed in your history of American industry.

For an individual to make $2 million a year for himself at a 90% tax rate, he would have to own 100% of a company generating $20 million in profit.

Assuming the same individual's skills were worth $200k/yr in market salary, you would be suggesting that the individual must have had a greater than 10% chance of growing a $20 million profit business to achieve an expected value of $200k/yr in compensation. You would be wrong.

However, if the individual only had to generate $2.5 million a year in profit through their business to take home $2 million a year, that 10% success rate is more realistic.