Because supposedly there are a few thousand people hoarding most the wealth like Scrooge McDuck, and more taxes will extract it so the common people can benefit from it. Never mind that people that rich can simply hire top-of-the-class accountants to find every loophole required to dodge those taxes, so the middle class will be stuck actually paying it."you pay more but you get more money!" -idiot logic
How about you take less so people actually have more instead of some weird Hollywood accounting logic?