How do you know? Have you walked in their shoes?

I mean, I don't have access to anyone's internal brain-state other than my own, obviously, but I have had at least one coworker outright tell me that this was their mentality. This coworker made roughly the same yuppie engineer salary I did, and didn't have any familial responsibility, and flatout told me that he didn't have much interest in saving money, he likes to spend it and live for the now.

Granted, I think that this is mostly a product of the fact that he was pretty young (22 at the time), and I haven't really talked to him in 11 years, so it's very likely that he doesn't do this anymore.

I'm not saying these people don't exist, just that judging is usually unfair.