One issue is with earned versus unearned income.  Let's say I have $100 million.  I can invest that in municipal bonds and get 1-2% interest tax free on that.  If I live on a million a year, I never touch principal (inflation  would) and pay no income taxes.  Or if I own a company and don't sell it, I pay no income tax because I have no income.  If I see part of it, having held it a year, I pay capital gains taxes on the unearned income.  I don't pay FICA on any of it.