First thing's first, taxes on capital gains should be much higher, and always higher than taxes on wages.

Second, loans require repayment. Even if the bank accepts your stock directly as payment, there's a taxable transaction. I don't understand how loans evade taxation.

Third, marginal tax rates used to be MUCH higher than they are today. Example from USA Today: "For married people filing jointly in 1953, for example, any income above $200,000 was taxed at 90%, above $300,000 at 91%, and above $400,000 at 92%."