A platform without ads or evil corpo ownership? Yeah, I'd scared too.
But Lemmy isn't growing. In fact, it's declining: https://lemmy.fediverse.observer/dailystats&days=1000
(When looking at these stats, remember that the post and comment counts are all-time comments/posts that are available at that specific day on the platform. In June 2024 there were more total comments than now, and in November 2024 there were more posts than there are now.
And all numbers are including the NSFW instance.