I don't know most of these people. But the ones I do, well, I notice two patterns,

One is that these are strong people. I mean that physically, but mostly emotionally. When life hurts, it hurts badly, but they keep going and keep trying to protect and be there for the people that they care about.

The second is that some of these are kinda snarky or give the appearance of not caring, but deep down they do, and when you get to know them better, they're warmer. And sometimes they run off or bail out on friends, but in the end, they come back when it matters most.