The Millionaire tax in the US used to be 90%. It payed for World War 2, the Eisenhower freeway system, and coincided with one of the most prosperous periods in US history. Oh, and most Millionaires paid no where near that due to deductions and loopholes.
It didn't stop people from becoming rich, more people actually did become rich, and the country had nice things, like levees that worked and roads not full of potholes.