How many democratic countries have never had some kind of involvement in imperialism, slavery, monarchy, starting wars, etc? How many are still doing it?
I don’t really think that individuals need to feel especially bad for getting work where there’s work.
Some jobs just inherently involve asshole clients. If your job is to stitch the leather interiors for Rolls Royce, 100% of your customers are assholes. I don’t think that means you should stop doing that job and flip burgers instead.
