Why do people argue like middleschoolers?

By that i mean, showing no respect at all to the opponent. Caring too much for the result of the debate only seeking a victory and nothing else.

I also have noticed that even when i win public debates with constructive arguments people still mock my opponent like as if he's a literal subhuman that got humiliated, and that's only when i win because when i lose on the other hand my opponents don't even respect me, and a lot of the time the arguments are very destructive with my opponent using everything they've got, from constant taunts to pressure me and just fallacies to win the debate and drop down my reputation while increasing theirs.

Why must they argue like that just to get people to think they're cool? i've read an article about how the people that gets humiliated are actually "deserving" of such a thing but i fail to see how every loser in a debate deserves to get his reputation lowered. Why does such a type of ego sadism even end up being overlooked and even praised by others?