It's still a big bet. Youtube gets views multiplication by the suggested video feature which redirect people from the random video they stumbled upon into the big ticket videos.

All the small creators also saturate the search space with all kind of topics and content, which drives people naturally via suggestions to the larger channels with fat advertisers, so the benefit is twofold.

Bet they did the math and they still come on top for now, but social are quite generational and live off the network effect, so there's that.