YouTube is one of the only groups that actually makes a profit..or at least gets close to making one - the metric seems to change with the economy.

Also it has a monetization model, which makes it infinitely more enticing than an instance that's more likely to cost money.

Finally the cost of storing and serving video is exponentially higher than images gifs and text, making it more prohibitedly expensive the more users you have.

Sure you could have a pretty ok system if they added a built in patreon like mechanism to peertube, with a revenue split. But it remains to be seen if creators and people are willing to negotiate and give up enough revenue in order to keep the server alive. And also it becomes a bit more businesslike - as you've seen with twitch, giving a worse split is bound to cause backlash and people to drop your instance, even if it's necessary to break even.

There's next to no chance you'll have an easy time if you wanted to migrate your account to another instance - especially if you wanted to keep all your videos. You'd probably have to re-upload them all as most migration setups on the fediverse don't move post data due to the prohibitive amount of data there is, more so for pictures and video

I think we'd be more likely to see pixelfed replace Instagram and pixiv than peertube replace YouTube.