Comes, because statistically those youtubers are able to latch on to some viewers and this drives engagement. I believe some of that has been pay-to-win stuff, where the youtubers actively advertised and paid directly for engagement. Some of those folks are subsidized by outsiders.

Goes, because YouTube knows from studying its own business that they're capable of driving more engagement by turning people into video-obsessed alt-right Nazis. And if it's too obvious, they'll be called on it, or actively punished as a platform over essentially selling themselves out as a propaganda bullhorn to whoever's able to pay.

That being the alt-right Nazis, and those who fund them.

So it goes back and forth. YouTube doesn't always do this. It does as much of this as it possibly can, but is systemically aware that running with it causes other problems, and dials it back to stay out of trouble (and because some of the people minding the algorithms are not, themselves, alt-right Nazis).

YouTube always wants to find an algorithmic answer for everything, and is not afraid to go meta and look at larger contexts for what they do. It's a google thing. So they want, and don't want, the 'own the libs' paid-for content. It's both simple capitalism, and looking at it on a larger systemic level where there are risks to allowing their ad buys to stoke outright revolution of the country YouTube is based in.