For me it was a combination of seeing that there was a lot of activity on the fediverse (no point joining a social media if there’s no people on it) and also feeling the need to actually frequently use social media again, because I hadn’t been using social media for a while outside of retweeting something once in a blue moon.

We’re social creatures, so I’m sure the more people move to Fediverse, well, the more people will follow.