It's popular. If everyone else has it, that means you are missing out if you don't. As a child, saying "No sorry, I'm not on instagram" means they're a social outcast in their heads. Of course, no one actually cares, but social interactions matter a lot at that age.

Edit to add: A lot of teachers are also trying to be hip and cool. Three times in the past year I have been assigned "tiktok" assignments where I either had to record a tiktok or watch a tiktok. Of course there were other options that I took, but if some kid doesn't have it simply because they don't care, not out of privacy reasons, they'd probably download and start using it regularly after thinking a grade rides on it.

That's another thing: I am 100% serious when I say that my peers are addicted to tiktok. I know people who regularly spend 6+ hours a day just scrolling through it. In fact, I don't know anyone who doesn't spend at least 2 hours daily on it. I don't think any other social media comes close to it in addictiveness. It is literally almost everyone I know, even tangentially.

A few years ago, I heard a couple of kids on the bus singing songs about how they’re going to be big on Instagram. It stuck with me as one of those things about how kids observe the world versus how I observed it as a kid.

So to answer your question, I don’t know how it would be appealing, but I think they find it appealing anyway independent of whether we know why, so it’s probably worth revisiting your priors.

I could be wrong, but I think a “whoosh” applies here.

Children like emulating adults and "older kids"