You are misinformed about the tax rate. The top Federal rate was either 91% or 92% (I can't remember which), and it applied to taxable income over a relatively modest base ($100,000?), and this went on for years and years. It was the reason that a lot of highly paid celebrities worked only a portion of the year: For them, most of their income fell into what you call the "marginal" portion of their earnings. They chose not to work the rest of the year for the government--and remember that there would be state income tax, in many states, on top of the Federal tax. Liberace in particular spelled this out for the press. When his actual earnings hit about $1,000,000, he would quit work for the year, since all additional earnings would have been taxed at the 90+% rate with no way to shelter any of it.
Tax rates really do have consequences.
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