Raising tax rates beyond that point is guaranteed to be suboptimal, though. Most of the weird distortions being discussed in this thread are due to the postwar 92% tax rates.
It's useful to know where the ceiling is.
There are many people today that argue we should bring back Eisenhower level tax rates on the wealthy, and there are many others that argue we have to keep taxes on billionaires at the extremely low levels they're at today or they'll quit participating in our economy. Neither of these is true.
The most extensive Laffer Curve study pegs the ideal top marginal tax rate at 73%.