John carpenter protags aren't supposed to be the pinnacle of human courtesy. They're supposed to be realistic depictions of john everyman being dumped into the main conflict. They're assholes because people who are forcibly burdened with saving the world aren't going to be happy about their lives being destroyed. They make dumb choices because the new conflict they have to face isn't something they're prepared to deal with. They have to learn to be a hero as they go. How those characters act is how most, if not all, people would react if placed in their shoes.

I feel like the character bothers you because you were expecting more of a competent self insert character like in modern dystopia movies, while john carpenter says "if you were forced to save the world, you would wish you could go home and watch tv instead, and you'd suck at it the entire time you're saving the world".