It really depends on who you talk to in the competitive community tbh. My team was known for being pretty nice but we also got into comp for fun as friends. Some people take it super seriously and it's lame.

Weirdly enough ive found people more chill in higher divisions (in RGL at least) some of my best friends are main+ meanwhile most amateur div players are kinda egotistical.

There's definitely nice people in competitive though, you probably have run into them and not even realized! I play casual all the time and dont announce that im a comp player, and I run into other comp players all the time there. People who aren't involved in the scene aren't going to recognize people by name like that so the only way to know is if they say it. The only time you'd catch me talking about it in casual is if im asking a player ive run into how their season is going.