I think it's already very hard to change our own habits. I would not hope to change other people's own habits.
I would like Lemmy to grow if only for one reason: I don't care being part of any niche (no more than I care being part of not highly popular communities, mind you). I enjoy exchanging ideas and chatting with interesting people much more than I need to feel 'smart' myself because of the tools I'm using and for any chat to happen one first have to meet people. So, the bigger Lemmy, the better for me ;)
I joined Lemmy/I left reddit only because I realised I was not OK with the way reddit changed policy (the way they control our content) and because I was not happy in the way they made their website evolve. That said, I do miss the few subs I was following and participating in on Reddit. I miss them a lot, as they were/are often very interesting and rich.... of their participants.
Can Lemmy become comparable? I don't know, I have some doubts but I also have very little intention to come back to Reddit, at least not until they change a few things.
After I announced I would not be posting on those subs anymore, a few months ago, two people contacted me to tell me that would be some kind of a loss and they were sad to see me go, asking me to reconsider. As far as I know, none have created an account here on Lemmy so we could keep on discussing stuff. Of course, I can't be sure of that but to be 100% honest the opposite would have surprised me a lot more. I had the same lack of reaction a few years ago when I quit Twitter and the likes. That's fine.
Changing habits is hard. Even more so online, I reckon.