In 1981 the first of Ronald Reagan's tax cuts was passed dropping the top tax rate from 70% to 50%. Five years later his Tax Reform Act of 1986 dropped the top tax rate again to 28% while raising the bottom rate from 11% to 15% where it remains today. The 1986 law also collapsed the number of tax brackets from 15 in 1984 to 5 in 1985. While lowering the top tax rate for the rich from 70% to 28% was a huge boost for the wealthiest Americans, compressing the top 10 tax bracket helped assure that the changes would not be undone. The reduction in tax brackets meant that the number of people in the top earners bracket went from tens of thousands of the riches voters to many millions of voters including those with much more modest incomes. By lumping together people making over $300,000 with those earning 10 times that amount or more, the change created a large voting block of voters who would oppose future tax hikes.
During these same years the Reagan administration began deregulating the banking and finance industries leading to more and more wealth building opportunities for those already blessed with riches.