I think it’s a bit fatuous to argue that altruism is just self-interest. Sure, people who volunteer or help others in distress usually get some kind of benefit. They feel good about themselves, or they get to live in world that is one trillionth of a percent kinder/happier because of their good deed, etc. But the self-interest argument falls apart when you look at it from a cost/benefit standpoint. Suppose a person spends 2h raising money for the food bank. The hungry people who gets to eat and feed their children benefit the most. The local community benefits a tiny bit, and maybe the volunteer gets a small self-esteem (and other-esteem) boost. On the other hand, if that person were to spend the time earning money for a nice sweater, say, they might get a bigger self esteem boost, a few compliments, and a warm fuzzy garment that lasts for years. The hungry person is still hungry, but remains an abstraction. I would argue that the sweater earner benefitted more than the volunteer. Yet, people still volunteer.

Some people make anonymous donations. Do you really think the self-esteem boost is more valuable than the literal money that person donates?

The argument that the world would be better off if everyone acted in their self interest is ridiculous. That inevitably leads to a might-makes-right system of oppression. The only reason this argument is still being circulated is because shitheads like elon musk, who already has a huge amount of wealth and influence, spam this shit everywhere (on Twitter, Fox News, etc.) to legitimize their undeserved status and evil power.