Why do I have followers on Instagram who never like or comment on my posts?

This is really common and it comes down to how Instagram counts followers
versus how the algorithm reads engagement. A follower who never interacts
still counts toward your total, but Instagram's algorithm only shows your
posts to more people if your engagement rate (likes, comments, saves relative
to your audience size) stays healthy. So a bloated list of inactive followers
can actually hurt your reach even though the number looks good.

The easiest way to check this yourself is to request your own data export
directly from Instagram's settings (Download Your Information), then run it
through a tool like igunfollowtracker.com to see who's inactive or never
engages. It uses your official Instagram export, not a login, so there's no
risk to your account.

Worth doing every couple months if you're trying to grow, since it tells you
whether your real audience is actually healthy or just inflated.