In my opinion the way to enter the social network market is using the Slack/Discord approach. Rather than trying to make a better Facebook for the world, make a better Facebook for people to use for their specific community or company, and then make it easy to tie your account to multiple communities, and then (maybe) start connecting communities.

I almost achieved escape velocity with Matrix/Riot in my gaming group a couple years ago. Ultimately it was too buggy for them at the time and we ended up on FB messenger, but if it had worked they'd all be primed to join a Matrix-based social network right now.