95% income tax would remove any incentive to go above and beyond and you end up with collapsing economy where everybody is doing the bare minimum. See Soviet economy outcome and tofu dreg buildings.
95% over 20 million. Average Joe is never going to see 20 million in his life, so it's not exactly a concern for him. You can adjust the value as necessary to only apply to the top 1-2% or so. You can still have 20 million, and even more on top of that if you keep earning. Just most of that extra money will go back to society instead of being locked away inside a bank account forever