I want to actively build community

That was the key for me. To take one of my favorite communities ("bande dessinée," i.e. Euro comics) and create a version on Lemmy eight months ago. It's taken a load of work (usually daily), and sometimes I get really discouraged, but overall it locked me in to the FV.

Also, you might have to burn me at the stake for saying this-- I still visit Reddit because of the far more prolific content, and do have worries & reservations about the tankie founders of Lemmy. But so far, so good. The more the FV grows, the more I'll have no problem leaving Reddit behind.