Well, as far as Lemmy goes most of the people who came over first are people who are technically and privacy oriented. Issues with Reddit causing several exoduses (I think I spelled that right).

What has historically pushed people to use Linux is the same driver for pretty much anything fediverse/activity pub. It's the early adopters that are going to shape the discourse for a while. I think Reddit was the same way at the start as was Digg.

Your average non-techie is less likely to want to figure out how to use Lemmy over just dealing with the other things the corporate sites are doing. Not that there aren't non-techies on Lemmy, but it will take time for them to overtake the techies by a significant degree, if it happens at all.