I have no problem accepting the Laffer Curve in theory, although I doubt that it would go back to zero. However, nobody knows what T* is. I suspect that it would change every year based on government spending.
One of the highest tax rates is 50% on people who take Social Security at age 62 and earn too much money, which could be as low as 30,000 dollars.
Even if tax rates are increased, the richest people will figure out ways to side-step them like they always have.