Ah, the “there is no such thing as altruism” argument. But perhaps reward and benefit transcends a single individual:
I mean, yes?
No one ever does anything for truly selfless reasons; so-called selfless actions receive some kind of positive reinforcement. Yes, when I’m nice to my spouse, they’re more likely to want to be nice to me. When I donate money anonymously to a good cause, I feel good because brain chemicals are telling me that I’m a good person. If you removed that positive feedback loop, then people would quickly start acting solely in selfish ways.
Doing good is good, regardless.
Absolutely. If we didn’t have this feedback loop in our brains, humanity as a species would die out in a generation. Psychopathy is super-bad for species survival.