It is about the skill of the player not the skin !!
Some player are so proud of their skin and making lots of talk and sometime bragging nonsense conversation ( I auto mute them ).
Then when they are doing good at the game they become boastful sometimes I just laugh. Even though it's just a game nothing personal I don't get triggered easily.
But my experience about league of legends most of the player I have met with good skins are quitting early sometimes rage quit HAAHAHAHA. Don't know why.
For me it's okay to have a skin or good skin in game but maybe the way you brag or you become boastful at the game is a meh for me, sometimes being toxic is not cool !!