There were a few big waves of people trying out Mastodon when Twitter first started shitting the bed. Everybody likes to blame failed mass adoption on their own particular grievance with the software (most of which are legit tbh) but imo the 'problem' was that it's no good for influencers (due to architectural choices) and most people want to follow influencers.

And there's no way to fix it tbh — you can't have a decentralized network and discoverability on a par with a centralized service. And many existing Mastodon users do not want discoverability anyway.