Thats the neat part, you don't. Social medias value isn't determined by it's tech. Its value is determined by who and what you can interact with. For example, people wont leave Facebook because everyone they know is on facebook because people won't leave Facebook. Twitter is literally run by a nazi at this point and still it's the same story where Mastodon and Bluesky aren't even close. Same thing for reddit and lemmy. Lemmy simply doesn't have the content reddit does, look no further than sports subreddits where any given game has a live game thread with a hundred or more unique commentors.

If you want mode people to come here you're going to need to do two things. One you need to post content people want to see, and two you need to get very very lucky because as it stands if you don't care enough about decentralization to lose out of a lot of content, theres literally no reason to be here. Its a long slow road and you're still going to need reddit to do something stupid before we see another growth spike.