People use YouTube because it aggregates content for people in channels, makes engaging with videos and their creators easy, makes discovery easy for users through search and suggestions and allows people to roughly measure notability and quality of videos through up/down votes, views, and a creator's channel subs. They make becoming a content creator as easy as making an account and hitting upload. They make monetizing that content as easy as hitting a checkbox.
Similarly, people could get around the privacy concerns and constrictions of big social media sites by having a self-hosted blog or something along those lines... but we all know that the chance of someone— even someone you care about— breaking the comfort of their daily digi-routine to visit your site and comment on your happenings is pretty much nil. If all of their "friends" did it, then the whole ecosystem... well it wouldn't be an ecosystem anymore.
EEVBlog is a good example of content that wouldn’t exist without youtube. Dave is a full time youtuber who can focus on creating content instead of making money some other way.
Dave is trying to move away from being dependent on YouTube, and he absolutely should, but he built his audience on YouTube in a way that isnt feasible in a world without algorithms pushing content towards people
as long as there's no easy revenue model for non-youtube content, people will continue to put their videos on youtube, because that's how they get paid.
Of course, not as convenient as streaming, and you lose the comment section (is that truly a bad thing, though?), but it is a viable solution that can be implemented right now. People are talking about "alternative" websites as if they will find some magic bullet on that path. But who will create that website? Who will maintain it? And if the answer to those two questions isn't "me", how can you guarantee that the same problem won't eventually happen?