Not everyone has eating the world as a goal. Lance Ulanoff didn't understand this when he declared Mastodon DOA two years ago because he couldn't find William Shatner, and people continue to make the same mistake. I don't want to follow William Shatner or Lance Ulanoff, so they can stay on Twitter with people who do.
If your goal is to have Mastodon "catch on" and have people transition away from Twitter en masse, then yes, you need William Shatner on Mastodon.
Even the main Mastodon project instance is funded by a Patreon. I don't think Eugen would complain if he had a few more users, but growth doesn't seem to be the #1 goal. Only the tech press and its target audience seems to care about how fast Mastodon grows. They are free to start a growth-focused instance.
The instance I'm on has 800+ active users. The numbers on closely related instances are probably similar. That's plenty.