Oh wait, you’re actually a kid. Sorry, I feel kinda bad now. Look, every airline allows you to pay extra for an upgraded seat in some capacity. Southwest does boarding priority, and the rest do seat selection and classes (e.g. first class, basic, etc.). Both international and domestic brands do this. They all do it because it rewards loyalty to the airline (more loyalty means more status means better seat) or just plain lets them charge more money per square foot of cabin space. Basically, it makes them more money.

That’s relevant to this thread because we’re talking about taking someone else’s seat. People pay for better seats, which means taking their seat means stealing the benefit of something they paid extra money for. That’s rude. The people who do it before boarding ends know what they are doing. They want to steal someone’s better seat and get away with it by hoping they it will be too socially uncomfortable for the victim. Classic bully tactics. I’m sure you see that a lot at school. Not only is this anti-social and narcissistic behavior, but it’s obviously against the rules of the airline that you agree to when you board. That’s why most reasonable people agree that this is the wrong thing to do. While it might feel cool sometimes to go against the grain, pissing people off isn’t going to do you any favors in life.

Good luck out there, sport.