Massive wealth accumulation isn't just about having money to buy things, it's about influence, and entities with the ability to marshal more than x million dollars per year (Apple, GOOG, Unicorn LLC) would still need to exist. If your policy became law what would stop people from simply dumping huge sums into businesses/non-profits that they control? I believe capping yearly income would introduce a lot of weird bugs into our system without fixing (m)any real problems.