You only have to watch the majority of passengers behaviour in the airport environment to realise once in an aircraft - they become even more separated from real life and pretty damn close to subhuman in many instances.
and
From my one experience of trauma I know that your brain does funny things
I'm not sure if it was a briefing about the Manchester Airtours accident or just during my training in general, but passengers in an emergency have been categorised as those who:
1) Panic and will climb over everyone and everything to get out and survive;
2) Are in denial, even to the point of sitting in their seat (reading a paper I was told), to the point where they do absolutely nothing;
3) Become agitated/violent;
4) Faff around carrying out out irrelevant tasks instead of making for an exit; or
5) Evaculate in an orderly fashion.
The latter, I suspect, will be in the minority.
Some might even assist cabin crew/help others, but they're likely to be a rarity.