"Nobody does anything for nothing. Altruism is beautiful in theory, but it has never been known to work in practice."
In “The First Lensman” by E. E. Doc Smith
In many or most written SF, certainly in SF films, the canny audience member engages in a willing suspension of disbelief. The question for me often comes down to just a couple considerations--is it a bridge too far, just too many stupidities of too gross a scale for me to be able to buy-in? And am I enjoying myself on other levels--is it just so fun or cool or exciting, or are the characters and story just so damned compelling, that I can't help but have a good time? So, if I'm not offended by the stupidity, and the work in question as a narrative, then I'm happily able to suspend my disbelief and enjoy it.
Ok. it's only SF but..
If you're into stuff like this, you can read the full review.