Not OP but a progressive tax generally scales non-linearly to tax higher brackets a higher %. So then you have an increasingly lower / decreasing incentive to make even more money.
Many countries already have a progressive tax on income, but that is irrelevant to business profits.
Yep, exactly. There's an easy way to make it gradual, too: put the "heel" of the progressive tax above where the largest American companies are and let inflation bring them into the curve. They can either pay a tax cost not to split, or they can split.
Alternatively, don't. I expect this proposal to be popular with executives regardless because it creates new spots for executives, just as it does with lower-flying labor.
Many countries already have a progressive tax on income, but that is irrelevant to business profits.