Maybe he owns the technology that powers reddit, but he does not control the community. Social media platforms have fallen before. Reddit only gained traction after Digg fell.
This is actually a huge problem for them - the general discourse on Reddit reflects values that the company clearly no longer holds. They're not as entrenched as they seem to think they are. Reddit produces zero content.
Reddit is just a forum host who's pissing off its users.
Also, lazyness is always a huge factor. It's will always be easier to just stay and so most will.
Maybe Lemmy is not for everyone, but 10 years ago you could have said the same thing about reddit.