AFrom a certain standpoint i believe but not totally that all people are self-serving. No one is truly altruistic. If you feel good after doing something good, then you’re still getting a benefit from your kind act. That’s self-serving. This i believe is true, although as with many things their are always two sides and as such id talk about both a bit.
The idea that every human action is motivated by self-interest, even those that appear to be for the benefit of others. The strongest argument for this point is the neurological reality of kindness. When you help someone, your brain releases a cocktail of dopamine. This is often called the "Helper’s High." If you give a thousand euros to a charity and feel a surge of pride or a "warm glow," you have effectively purchased a positive emotional state. From a strictly biological perspective, this is a transaction. You traded currency for neurochemical pleasure. If the act made you feel miserable, burdened, and depleted without any internal reward, would you ever do it again? Most people argue you wouldn't. Therefore, the "benefit" is the feeling itself. Consider the person who donates a wing to a hospital but insists on remaining anonymous. On the surface, this lacks the "selfish" benefit of fame or social status. However, some people would argue that the donor is seeking a superior internal narrative. They get to feel like the "type of person" who is so virtuous they don't even need the credit. That internal "pat on the back" is a potent form of self-service.
Then their is Reciprocal Altruism which is when people provide a benefit to another with the expectation that the favor will be returned in the future. Even if a specific person never pays you back, "good deeds" build your social reputation. For example If you spend your Saturday helping a neighbor move furniture, you might feel tired and gain nothing immediate. However, you have successfully "insured" your future. You have signaled to the community that you are a valuable. Should you ever need help, the community is now "indebted" to you. By helping them, you have increased your own safety net.
As seen in Maslow's Hierarchy, "Self-Actualization" sits at the top. For many, being "the best version of themselves" involves being seen as a savior. This feeds the Ego. Even if you don't post about your deed on Instagram, the mere knowledge that you are "better" or "more moral" than the average person is a massive ego boost. Imagine someone flying to a disaster zone to hand out water. It is grueling, dangerous work. However, for the rest of their life, that person possesses the "identity" of a hero. This identity provides immense confidence, social leverage, and a sense of purpose.
But then we ask ourselves at the end of the day, Isn't it a good thing that our brains are wired to make us feel good when we do good? If nature had made us feel "high" only when we were being cruel, the world would be much darker. If the "benefit" of being kind is a sense of peace or a "warm glow," then "self-serving" behavior is the very thing keeping society together.
On the other hand or ither side of the spectrum, an argument could be made that when a person jumps onto subway tracks to save someone who has fallen, they aren't calculating "warm glow" or social capital. The "fight or flight" response is instantaneous. In that split second, the self is bypassed. The survival instinct the most "selfish" thing we have is overridden by a drive to preserve another life. If the benefit was the goal, the risk-to-reward ratio of dying for a stranger makes no sense. Anpther example is parent who works three jobs to put a child through college, sacrificing their own health, sleep, and hobbies, may feel "happy" that their child succeeds. However, the happiness is a biproduct. If you offered that parent a "happy pill" that would give them the same feeling without them having to pay for the college, most parents would refuse it. They don't want the feeling of their child being successful they want the actual fact of their child being successful.