I'd rather build something new and actually have a userbase than be something akin to a subreddit with fleeting users. It will be a lot more hard work, but it's worth it.
Also, Mastodon sucks. This whole "let's be free together" but also "don't step out of line" culture is disgusting: https://news.ycombinator.com/item?id=28495086.
> The obsolute worst thing about the Fediverse (Mastodon et al) right now is the onboarding process. You have to "chose an instance" before you can even start understanding what that's about - and if you chose wrong you might find your instance gets switched off leaving you high and dry in the future.
That's the problem. It's unnecessarily complex and other than a subniche, people in the real world are not interested in it. They just don't care about this at all.