I can't speak for everyone but I'd assume so, yes. Unless you happen to be a god (for your skill level) that can legit carry every game, clutch endless rounds every game, etc at some point you will hit a losing streak and derank. It can happen for a variety of reasons. Maybe you are playing decently well but you get unlucky with teammates? Or maybe you aren't hitting your shots well and throw a bunch of winnable rounds? Or maybe you hit several games with smurfs/cheaters? Or sometimes the other teams are just flat out better than you? Or, most likely, it is a combination of all of those things. But at the end of the day I think most people that grind out comp don't just rise and rise and rise without deranking a few times, again, unless they are just a god for their skill level.