First off...these guys may be thugs, but at least they're honest about it. Their stories are consistent with each other and they don't seem to be hiding anything.
The first guy seems to realize what he did was wrong. He makes a good accomplice but doesn't seem to be extremely violent. The second one is a reptilian killer, and he really made a point when he said, "I don't have anything to live for. I don't know why I was even born." and "My life so far has been Hell. Capital H, E, L, L."
I believe in personal responsibility but the reality is that these guys have been molded into cold-blooded killers by their home lives, environment and glorification of violence and the ghetto promulgated by the media. This is a serious problem and needs to be changed. That second one was clearly screwed up early on as a kid, but it doesn't need to be that way.
These people are very scary, and the second one is well on his way to becoming irretrievably evil. Someone who doesn't care about living or dying will not hesitate to shoot someone whether they hand over the money or not.