On every platform you’ll find people that have reviewed thousands of books, posted hundreds of thousands of comments, attended every single event in the sector, have 1m+ friends etc..
But it’s bunk to think that you can recruit them.
It’s almost impossible to identify them. Previous experience in other communities/platforms doesn’t predict future effort. In fact, those highly active elsewhere are less likely to be highly active in your community. Why would they participate?
It’s hard to identify them by personality type either. Slower self-esteem might cause higher levels of participation, but so might the opposite.
The best you can do is recruit a bunch of people, provide plenty of opportunities for those that put themselves forward, and nurture the ones that do. Not all will become superusers. The secret isn’t to pinpoint them at the beginning of the funnel, but to increase the size of that funnel (especially the immediate post-registration moment).