Why do some people act like its the other person's fault when they get rejected?

I just find it so amusing when people get rejected they find some way to make it seem like they were better than the person who rejected in the first place. They say things like " whatever its their loss" or " Pssh she'll never find someone as good as me anyways". Or the classic " Ugh he's such an idiot what did i see in him" lmao. Why cant they just accept that the other person didnt find them attractive for some reason or the other. Use it as a lesson to improve and move forward amicably instead of tearing down the other person to make themselves feel better, and hating on them and everything they do. Sorry for the rant I rejected this girl recently and she flat out told me off infront of everyone I was so embarrassed...... wow!