I can't speak for everyone. I've been lurking for the past couple weeks and just signed up yesterday. The prevailing attitude I've noticed is that people realize just how much of a toxic hog lagoon reddit has become, and are glad to participate in a community that isn't. It's nice to be somewhere that isn't full of bots and doesn't coddle nazis.
I also think it helps that most of the onboarding literature is frontloaded with "this is how federation works" instead of jumping right in to "here's how you sign up and use lemmy." Effectively scares off the reading-averse.
If considering that to be a plus makes me an elitist, I'm ok with that.