It's driven by the fact that many of these people work for companies doing similar things, and this is how they resolve the cognitive dissonance. Otherwise they'd have to accept that their work is unethical.

I've wondered about cognitive dissonance. Another "cog diss" possibility is, maybe I have a strong aversion to admitting that I'm getting screwed. Maybe I can relieve those feelings by arguing publicly that I'm not getting screwed. Or that it's "inevitable" for me to be screwed.

I don't know. It's one guess among many.