More than you might think. 1 in 20 people make over 200k / year. 400k is not enough to get someone into the top 1%.
So, several million Americans are making 1/4 million + per year before taxes. Which is why millionaire does not really qualify someone as rich anymore. Consider 1 million in 1915 is the equivalent of ~25 million in 2017 which is closer to what most people think of as rich.