All the worst cheaters say everyone cheats (which apparently is enough justification to supersede their own public marital vows.)
Arguing that people are universally terrible is a huge signal that the person making the argument is terrible. Don't go into professional partnerships with them, I've seen at least 3 people like that whose behavior has devolved into eventual jail time and they've wrecked their companies.
The world has a surprisingly high percentage of amoral assholes who have a vested interest in pretending everyone is as misanthropic and self-centered as they are, but it's still a small minority.
So what? What is wrong with that? We can't even understand our own motives, let alone attempt to decipher others'. Why not let the action speak for itself? If you're a selfish person prioritizing your own PR above others' needs, your actions will ultimately reflect it, and we can judge them on it. Otherwise, kudos for finding and pursuing something that aligns nicely with your own needs as well as the needs of others.