They'll generally choose convenience over a better path. This ranges from the people who just leave grocery carts in the parking lot, to people who stay on the platform formerly known as Twitter as opposed to being a part of supporting more ethical alternatives, to people who defend the data harvesting practices of big tech companies, just to name a few examples.
Twitter should be one of the easiest social media platforms to leave. Mastodon seems every bit as good as Twitter with the lack of users being it's only real flaw.
The microblog style seems to work the best with federation as well since you're following people.
I tried to switch to Mastodon a few times in the past, before the twitter issues were even happening and I could just never get into it.
And you're right, the only reason I was ever on twitter is because I was following artists that weren't anywhere else. Now I'm not on there and some of those artists never moved platforms because it was a hassle for them to and they risk losing their audience when they move platforms cause you can never just expect people to follow you as an artist.
The reason a lot of people don't leave the big platforms is that everyone else is there, especially if it's your way of staying in contact with friends.
I found it easy to ditch all "traditional" social media, expect for Discord (because all my friends use it), Yes we could all very easily switch to Matrix or some other open alternative, But 95% of people ain't gonna do that anytime soon.