Obviously it's marginal, and so is this whole argument, tax massive amounts of wealth (at that time it was anything over 200k (2 million in today's dollars at 90%), not your average Joe. Keep grasping at straws. And yeah make as much as you want...

* make 2 million = get 1 million (50%)

* make 3 million = get 1.1 million (63%)

* 10 million = get 1.8 million (82%)

* 100 million = get 11 million (89.1%)

* 1 billion = get 101 million (89.9%)

Make as much as you want.