I don't really bother until they're looking for an alternative.

When I've put people on Linux, to make an analogy, it's basically been because they entrust me with their choice of new computer, not because I won an argument about the relative merits of different software licences.

Most people IRL aren't even on Reddit, so Lemmy wouldn't make any sense for them. People might be on Twitter, but for whatever reason it hasn't come up, so no Mastodon either. Mostly I hear about Tiktok and Instagram for the young, and Facebook for the old. Pixelfed is Instagram-ish IIRC, but I'm not sure how active it is.

Edit: And if people want whichever platform they have the most friends on, well, they're obviously in the last 50% of the population you can recruit.