He appeals to the worst in some very influential people, basically "Get in the car losers, we're going Naziing". And all these rich people just happen to have a deep seated urge to go Naziing that societal ethics hasn't allowed them to explore before, so they just give him all their money.

That, and in a quid pro quo for their investment they'll obviously expect DHH to be even more of a Nazi than he has previously been. There, that's his "masterclass". Still impressed?