We don't need to have every human care about every single other human to thrive as a species. If anything, if we did, we wouldn't be able to thrive at all.

The issues you mentioned are, in the vast majority of cases, caused by the lack of peaceful coexistence to begin with, because as long as me and everyone else is coexisting peacefully, getting more for myself isn't taking anything away from those in the situations you mentioned. Resources might be scarce, but that doesn't mean they're zero sum.