Yeah, there's no way they're that rich even if they make 3 mill on Patreon. Taxes for this sort of thing can be a minefield, and that's not counting studio rent, production costs, etc. They don't do sponsorships either. With money split between Mike, Jay, and Rich, they're probably comfortable. But I also don't think they have kids. So unless they all have obscene stock portfolios or something, it's unlikely they're loaded.
Ugh, I just feel creepy talking about this. This Shatner thing is getting truly troubling. This isn't even the first time he's brought up their money. I half expect Mike to find some PI Shatner hired rifling through his garbage soon.
Edit to add that the site Shatner is using as a source LITERALLY HAS A TYPO.