On the Black Buffalo Soldiers

I could never quite get my head around this one. You have these former slaves who you'd think would have at least a modicum of empathy for other oppressed peoples (the Plains Indians and ultimately Filipinos) not only NOT having said empathy but actually going around slaughtering these oppressed folks. I mean, I know that there probably weren't a lot of other jobs available but, still, plants some damn crops, learn to shoe some horses, anything but genocide.