Because most men are fucking psychotic in a masculine/I deserve all my eye sees way. It's baffling. But being the polar opposite of that, I've learned that most of the women I have met want some form of that "kind" of man. Not to say my sample of interactions is grounds for real debate, but in my particular circumstances and experiences, when I'm uninterested or the other party is not, I'll be questioned as to why it doesn't seem to matter to me. It's a weird Dynamic. I love people for people, and if someone does not "like" me back I'm simply okay with that because I'm okay with myself..which many men are not.

It happens in both directions. I've had women get downright nasty with me for not accepting their advances. I think there are jerks on both sides of the gender aisle. Most men handle it pretty well, as do most women. Most men are used to rejection. If he doesn't take it well, that just proves your judgment of character is spot on. He's someone you really didn't want to be involved with.

It goes both ways. Men in general are used to rejection since we are expected to, and the vast majority of the time, have to make the first overture. This fact skews the numbers. Women can get just as nasty as men when rejected. Women are just not put in that position nearly as often as men. It isn't even close.

I've only had that happen once and I decided it was because he was a psycho. Of course there are all different degrees of anger but usually my experience has been one where the guy is only visibly disappointed but not angry.

I do not get that. As a human species, we are all attracted to different people. Sometimes it is a match, others it is not and that is ok. No need to be rude about it. I think a thank you for your candid reply is the best response.

There are certainly many reasons that rejection may manifest in anger. Anger is an easier emotion to deal with as it can be directed outward whereas rejection causes internal questioning. "It isn't me it is her".
As for the expression of that rejection in profane and/or derogatory comments, which we see often in internet postings, they may be the result of the person not having the ability to express themselves in any other way and the lack of consequences for such expressions. These people seem to have a need to have the last word.
Our society has become more accepting of crass behavior, the rise of women demanding a voice and equal treatment in a male dominated and privileged society and ego issues have been discussed. And all may a part in why name calling is acceptable to those who choose to do so.
Having said that - the problem will not go away. People are what they are and each of us has to know that such behavior is not our problem - but theirs.

I see it as a sense of entitlement, something that is becoming more common with the advent of social media and the anonymity that it provides, so people feel free to express their baser instincts. There's a lot of discussion lately about toxic masculinity, which I suspect comes from a lack of emotional intelligence.

There is an easy answer! Some "men" are actually very immature!

Most men just wanna fuck plain and simple

Their brains are immature

Their pride is hurt. when you reject a guy you crush his ego it's basically a defense mechanism

The best thing you can do is avoid them