Technology

It's not a pure monopoly by choice. While it's true Youtube has a monopoly in terms of number of creators, viewers and content, it's still not a profitable venture. I heard it was burning through money to keep up with the sheer amount of content they have to deal with. Youtube is doing all this monetization now because they have ran out of VC money and upper management decided that it needs to be self-sustaining. Even the obscene amount of data Alphabet is gathering from Youtube does not create enough revenue to generate profit. But it's a "too-big-to-fail" product now so Alphabet will continue to invest. Competitors saw all of this and just noped out.

Other commercial video services, like Nebula, have popped up but they are subscription-oriented right from the get-go, like Netflix. This means they have a very small audience and it will take years to build up an audience like Youtube. So I don't see them growing, at least in the near future.