Youtube is still the biggest video website on the world and there just isnt a viable competitor to it and nor is there financial incentive for anyone to jump into something like it given the overhead and cost. Hell even early on when youtube was lower resolution and ran worse on hardware it still beat out competitors like vimeo, dailymotion, and the various early internet content creator sites that spun off of youtubes early copyright purge.

At the end of the day they serve a tiny amount of ads which honestly is more of a minor inconvenience(especially when you remember what TV was like) and the algorithm is pretty hit and miss(personally on my feed it's not bad). Even worst case scenario if the adblockers stop working youtube will probably still not die.

It would take an antitrust hearing or something to really push youtube off of it's top spot and it would be interesting to see what that would look like for the site(though I suspect a google dismembering would leave youtube intact and just remove it form other alphabet brands which wouldnt entirely fix the issue).

Hell look at what happened on reddit. That was a very visible very big protest and there was a huge amount of outrage and reddit skews nerdy enough that the userbase actually pays attention and cares about whats going on. Weeks later and not a lot has changed. Lemmy and some other alternatives became viable but even then it And thats essentially just a big message board which links to content on other sites, in terms of design it should be easier to replicate compared to an open video site that anyone can upload to.