There is nothing wrong with software here
The point is that we would play KK ten times more than any lower pair, so 10 times more chance to lose a hand. And if we would lose with QQ e.g. against KK or AA, we say "oh fine it was a higher pair".
The thing is that if you hit a set with KK you will be like "Oh okay, fine, but I didn't really need it to win" and it will fly out of your memories, but if you get beaten by a set (or you can beat KK or AA with your own set) then it's more like a crazy feeling.
IF you would actually start counting all your hands and results and put them in a table, you will see it all fits Psychology is just way to strong