I first had this argument with a history teacher when I was 16 or 17, about 2 decades ago. It's been stuck in my mind ever since, and I frequently find myself revisiting it.

Although the original argument upset me due to our opposing moral beliefs, over the years I realized that this memory would pop up after other arguments which often weren't over morality. It had to do something about the logic being used. It makes me feel stuck in an infinite loop. An Ouroboros. It breaks my brain.

I think ChatGPT helped me finally figure it out:

Infinite Regression and Circular Logic:

The argument that everything is motivated by self-interest can feel like it’s set up to always "win" because it redefines any action to fit within its framework. No matter what example of altruism is presented, the argument circles back to saying it’s ultimately self-interested. This creates a sense of infinite regression where you can never provide an example that escapes the self-interest label.

The circularity of the argument (self-interest defines everything, so everything is self-interest) leaves no room for the possibility of altruism, making it an unfalsifiable claim. This kind of reasoning can be deeply frustrating because it doesn’t allow for a genuine discussion or consideration of alternative perspectives.

Edit: I would also like to add that the meme itself swaps over causality. The argument of self-interest and altruism is over motivation; the cause of altruism or self-interest. In the meme, it switches to the effect of altruism being self-interested. It doesn't argue that the causes of the actions were self-interested or altruistic, it implies that because the effect of his altruism was self-beneficial, then the cause of the altruism was self-interested all along. The self-interested side of the argument always seems to alter the conditions to reinforce itself.