Wait for the centralised thing to fuck something up (and they will), then say “hey I’ve been using this to get away from all the bullshit of [service name]”

ii suspect that most on lemmy have been moving from one platform to another since 1990's because of this sentence and it boggles my mind someone repeats it like it's never happened before.

Yup, interacting with and posting with content on these platforms is the best way, people trickle in to see what it's like. I doubt we'll ever have a big migration, the goal is long term sustained trickles