It's really hard. I got hit with imposter syndrome pretty bad not too long ago because someone whose writing I really like had posted a fic with a similar premise to one I'm working on and their fic blew up while mine has almost no one reading it. It's impossible to keep yourself 100% from comparing, if we didn't, we'd never improve upon our craft. The important thing is to remember that this is a hobby and hobbies are meant to be enjoyed. It's nice to have a few close friends that'll hype you up and cheer you on. It makes the writing process feel less lonely. (Idk if any of this really helps as advice.)