In the Netherlands, his bonus and income would have been structured differently, he'd have had a personal holding to 'catch' the money before it would have been taxed income or capital taxes, and he'd have paid next to nothing (yet). He could have delayed selling off stock to pay taxes for as long as he'd have wanted.

I'm not sure how entrepreneurs do this in the US, is Musk being patriotic paying so much taxes, or is there really no way to delay/avoid having to sell stock to pay taxes?