They were pretty clear with the job for Office Space, they worked for a bank/financial institution and had to update the software for Y2K so the years could accommodate 4 digits. That's why they were able to take push an exploit that allowed them to keep the rounded penny in a transition for their scheme, which may or may not have been inspired by Superman III.

They sold paper at Dunder-Mifflin? It was pretty clear

The premise of Office Space was that they were correcting the Y2K bug. And this description of a small, over-managed, haphazardly administered IT company is a very sincere reflection of how the industry functioned in the 90s. The punchline at the end - where you've got Ron Livingston shoveling asphalt with zen satisfaction while Diedrich Bader shakes his head in disgust - really does sum up the Dumb Guy attitude towards bullshit-but-ultimately-pretty-cushy office work of the era. But I wouldn't say they were doing nothing.

The Office was a reflection of dying backwards industry - in this case, the paper industry in Midwest Pennsylvania - that attract a certain assemblage of idiots and assholes and failkids in its waning days. This was more a story of a historically productive industry dying out.

American Psycho is much more about the Wall Street peak of power and the sadomasochistic personalities that populate it. I think its more comparable to Fight Club, in so far as it's a story of someone driven insane by the higher end business world and left to discover how thin the veneer is between civilization and barbarity.

And feeding stray cats to ATMs

American Psycho