That’s what I said. People stay on YouTube because the content is locked there. If you could watch YouTube videos from Peertube without ads, I believe people would migrate and YouTube would be forced to be less aggressive with ads. I agree that’s partly because content creators do not post their content elsewhere, but that’s exactly why fediverse is nice : the content is everywhere, you can’t lock it into a single instance.
The reason for switching from Threads to fediverse is the same reason why you already left mainstream social networks. But people not aware of its existence, or locked there because the content and the people they interact with are only accessible from there, they can’t leave. That’s why many people keep a Facebook account, or why people tried Mastodon and came back to X a few weeks later.
In my opinion, if a platform can only be different from the other because of the services it proposes (instead of relying on its own content), people will be able to move easily from one platform to the other (and they will if Threads starts to abuse its position). You are afraid people will never leave Threads, but the truth is that as soon as they will have to suffer ads, they will try to find adblockers or alternatives to eliminate them. The fediverse can be this alternative.