The rich certainly do engage in their fair share of irresponsible behavior, also - it's just that they're generally better at managing appearances and externalizing consequences. In fact, quite often that's exactly how they got to be wealthy in the first place.

So while people in the lower economic brackets might engage in overtly self-damaging behaviors like smoking or eating poorly (in disproportionate numbers) -- or simply be too depressed to look for work in an economy that basically has no use for them, or to go to college for an advanced degree in their 40s or 50s -- folks in the bulge brackets will end up doing "responsible" things, like voting for the political class that brought us the invasion of Iraq (including 500k+ killed and the bloodshed we are seeing up to the current day), climate change denial, and the (artificially accelerated) deindustrialization that killed off the middle class jobs those (now) in the lower tiers might have had access to in the first place, a few decades back.

In the world of work, while exceptions exist, I've always seen a strong correlation between position and competence.

In a sense this is almost a truism; one simply has to ask "competent at what?" In many organizations, unfortunately, it isn't technical or domain knowledge, or even interpersonal skills that merits promotion -- but simply the art of "managing up."