This actually goes back to slavery. Black men invented being cool - literally. And it is a skill. A survival skill. It’s been passed down through generations.
I remember reading a whole paper on this. During slavery black men had to reclaim their masculinity in the face of deadly consequences by maintaining composure and being willing to walk away from fukk shyt. Emotionally reacting would get you tortured and killed back then.
There’s a book on the history of it as well. Black Cool: One Thousand Streams of Blackness
Here’s an article:
@IllmaticDelta can prob shed some light on this