Jeri brings up a very important factor, stupid people, they were the ones marching up the tower stairs to save the 'smart' money changers and staff who were coming down. The firemen were servants and not all in it for themselves.
Stupid people can be decent honest people and not the white 1938 nationalist american militia.
My point is that stupid people aren't stupid, they are human. If they don't see the person next to them react to smoke or fire they are likely to ignore it too. Antivaxxers, american Taliban insurrectionists, alcohol abusers. can be stupid but they are not all stupid people.

The other factor Jeri brings up is that there are no stupid people here. I find that fanciful at best. We're all stupid about something.