Egoism

I notice this site has no posts about egoism, this isn't surprising as egoism is often overlooked in society, but my question is why? Egoism is a very fascinating philisophical theory but also scary to some, it basically states that everything people do circles back to some sort of personal gain, like even if an act is selfless there was still a personal gain that was sought after wether it be emotional gain or making/maintaining a friendship or connection, and you wouldn't have done it without some sort of root personal motive. I believe this theory has a lot of evidence and is pretty difficult to just classify as a "theory". If this theory where true then that would mean those who do not follow religion have no logical reason to care about other people outside of empathy if they can get to whatever there ultimate goal may be easier by being selfish. This would also mean nobody is truly a worse or better person then anyone. So is this theory willfully ignored or is there just some sort of obvious counter argument I'm not seeing because it's like most people who look at this very valid argument just see it as schizo rambling.