By uncomfortable, I mean sharing humilating or shameful details about their past life, making fun of their insecurities, doing actions that clearly make the other uncomfortable (like touching them or kissing them), etc.
I don't doubt there are people that get a kick out of degrading others. But it doesn't feel it is the case for the majority of people who act like this. I believe for most people it is simply that they don't see their victims as human deserving of empathy and find the reactions of their victims funny.