I wouldn't worry about Lemmy having as many users as reddit in the short term. Success is not just a measure of userbase. A system just needs a critical mass, a minimum number of users, to be self-perpetuating. For a reddit post that has 10k comments, most normal people only read a few dozen comments anyways. You could have half the comments on that post, and frankly the quality might go up, not down. (That said, there are many communities below that minimum critical mass at the moment.)
Lemmy is now a real alternative. When reddit imploded Lemmy wasn't fully set up to take advantage of the exodus, so a lot of users came over to the fediverse and gave up right away. There were no phone apps, the user interface was rudimentary, and communities weren't yet alive. Next time reddit screws up in a high profile way, and they will screw up, the fediverse will be ready.
Lemmy has way more potential than reddit. Reddit's leadership has always been incompetent and slow at fixing problems. The fediverse has been very responsive to user feedback in comparison.
My problem with Lemmy is the lack of activity in niche communities. You're right that there needs to be a critical mass and arguably Lemmy has it, but only for the most mainstream, generic type of content. It doesn't have the mass to sustain any sort of niche, outside of maybe tech related topics because of the way the userbase is slanted.
I find myself going back there often because of that, but I hope that the userbase for generic content enough to sustain and grow, from where more active niche communities can spring up.
Oh, I see you have zero posts, ever. Well why don't you go and contribute to that niche community you are nagging about. Maybe that's what it needs to grow.
Lemmy needs both content generators and content consumers. Not everyone needs to do both if that isn't what motivates them to come to the site.
I don't really love comparing to reddit because what reddit became isn't what I hope for lemmy, but to make the point... What percentage of people do you think made content on reddit? I'd guess it was a fraction of a single percent.
I am of the opinion that cameras don't really matter, beyond a certain technological level. Does it take pictures? Then it's a camera, capable enough to use. There was a quote in Michael Freeman's book on visual photographic literacy that I found quite interesting. He wrote that only ameteur photographers obsess over camera technology and settings.
I think things could get a lot more interesting if other software that is more like classic bulletin boards and forums would implement ActivityPub. I mean, such online forums are still able to thrive in their respective niches. If such forums would become compatible with Lemmy, Kbin or Friendica, it could bring a whole new dynamic to this part of the Fediverse. At the same time, it would help these niche forums get more attention (even though I'm not sure if all or even most of them are interested in that).
When I first looked into Lemmy, which was probably well over a year ago at this point, I saw that they had an alternative front end called LemmyBB which resembles the older style phpBB boards of the late 90s and early 00s. It looks like the demo instance is offline now, and it wasn't federating to begin with, but it certainly looks like an interesting use of the tech.