He's wiped out nearly all of the profit in the markets for the entire year.
And why would he care? His investments are in real estate. And he assumes, perhaps wrongly, that his base isn't in the market either. What he doesn't seem to realize is just how much he's pissing off normal Republicans. Or how much at least some of his base may become when they start feeling the effects of all these tariffs.
I think he's only doing it, really, because he can, and nobody can tell him he can't.