Firstly what is wrong with men that find no redeemable qualities in a woman yet date her and then proceed to destroy her self esteem?

I saw that situation so often in some of my peers lives, more than anything high school and then extends to some early 20s couples, dunno if after, but It was quite common (not every man, most men are actually not this way, but we all heard of it at one point) to the point I'm still scared of ever coming across one of those guys. They insulted the girls, put them down, put everything they said down, any compliment towards them down. Something teen girls do often is said "I don't find her that pretty" and that kind of guy seemingly can't wait to come up with the "jealousy" "she's better than you" card.

Why they've got to be so vicious? If you don't like someone then why don't they just don't date them? What leads to someone being so bitter to the point they grab some person that's done nothing to them to use and ruin them?

Boys who do this garbage are barely if ever attractive too, so why they feel such contempt for a woman that's giving them their time and attention, sometimes their love too as if they feel they deserve sooooo much better that they can threat a human being like garbage?