I think you're just fundamentally misunderstanding what being rational means. There is nothing inherently rational in being selfish or only caring about your own goals and what benefits you, especially not when you are a member of a species that evolved to be extremely social and community focused. Emotions and feelings aren't inherently irrational either. They can certainly be expressed in irrational ways, but they themselves are neither rational or irrational. They're just a fact of nature. You might as well say it's irrational for living creatures to have to excrete waste. Sure, it may be irrational to take a piss on your boss right before asking for a raise, but the act of taking a piss is not in itself rational or irrational. It's just a bodily function. So if you refuse to take that factor into consideration because you claim it's irrational, well that'd just be ridiculous.

Imagine a teacher refusing to let a student get up to go to the bathroom because they claim it's irrational to need to take a piss, and therefore perfectly rational to force them to stay where they are and ignore their bodily needs. The teacher is being selfish in that situation, only making optimal choices in pursuit of their own goals (to teach the class without interruption), and doesn't care about the other person's need to perform bodily functions unless it benefits them. And yet I think most people with even half a brain cell will agree that the teacher in this scenario is not in any way shape or form acting rationally. They're just being a dickhead.

Sociopaths aren't more rational than other people or "too rational", they lack the ability to feel empathy or they only feel a small amount of empathy but not enough to affect their decisions. It has nothing to do with being rational or logical, sociopaths can often be very stupid irrational people. Not to mention, while sociopaths often don't care about how other people feel, they do often care about how other people perceive them.