In my reading, your post implies that everyone is exclusively motivated by short term self interest. I do not think this is true, neither for myself nor for others, and I suspect you do not either for yourself and people you know.
The problem in general with negative fatalistic views like this one is that it is non falsifiable: there is not a single positive / selfless action to which you could not ascribe base motives.
That's the problem with assuming you can read people's minds, which seems quite frequent nowadays. The key "tell" for this is saying: "so what you're saying is" followed by the opposite of what the person is really saying.
The problem in general with negative fatalistic views like this one is that it is non falsifiable: there is not a single positive / selfless action to which you could not ascribe base motives.