Because the world is run by the dark triad of personality traits. Everybody is aspiring to be james bond because those traits are what lead to power/money. That's just my opinion and I know it is extreme but that's what I think.

To damper it a little there is a spectrum of this learned behavior. Some people are more sensitive and some more cold than others. I think a lot of us (mentally ill) tend to fall on the more sensitive side vs the dead inside.

As far as shameful, it is not your shame, it is their shame being projected onto you. Emotions are a gift, you are just not fitting in because earth is a jungle. Think lamb living with wild animals. Again, my opinion and I dont know you so I am making some assumptions here.

Out of control emotions are overwhelming for stable people but I feel like that hysteria is the results of years of no one listening and prolonged pain. At least that is how I feel it is for me. I guess everyone is different but that's what I've got.

Also, i think people just naturally avoid people in pain whether they admit it or not so shit just gets worse and worse and they accidently, or the worst of them, shame you intentionally to stop your cries. It is all a very sad state of affairs IMO.