I agree with you and will die to defend that position, but what existential reasons do we have to behave well? In reality, it seems like humans are just a bunch of animals, and the only important thing is survival.
My wife, just today, told me that she was very upset that I refused to interview and take jobs for things like building weapons, the panopticon, or advertising (two of those are the same thing), which I refuse to do because of my personal morals and ethics. How do I explain to her that I just can't do that, and give her a good reason why we should lose our home and live in one room with her mother because of my brain refusing to work in such industries? I really want to know, so I can explain to her and my son why such things matter, because for some reason they are concrete and foundational in my brain, there is no changing that.