why do people collectively behave irrationally?
116321
And you want a rational answer from here?
34702
You're getting into some pretty deep issues here. \n\nFirst off, people who need to justify and affirm their own value need to lower the value of others by doing what you're talking about.  This gets into some pretty deep biology and psychology.  Since humans are social animals there is always a social heirarchy.  When someone is at the bottom or middle and wants to move up, this is one of the ways they can feel a little movement.  Immature people will also do this in retaliation to an attack on them by another immature person.  It just turns out to be a self licking ice cream cone.  \n\nI used to think that I had to respond to everything in my honor.  Now, by letting things roll off my back and exercising my personal boundaries, I live a life with a lot less stress or anxiety.  Life is great!
472525
Cause humans are mostly insecure and conformistic.\nThey thus need an easy way out of their dilemmas as well as the relief of afterlife and the feeling of low responsibility adhered by religions(even if their dogma claims otherwise).\nMoreover there is a natural tendency in humans to belong in groups. A strongly structured group requires an opposing group. Religious groups provide both these features in abundance.
1081382
Maybe because they have no illusions. they see themselves as they ARE, those around them as THEY are, or the WORLD as it is. For rational people it is hard to find comfort in the way the world is today, though it is best to accept what is and do the best one can. No?
332284
Because they are self centered. But some of us are not.Hint Hint
956165
People find comfort in believing others are like them. They created a "normal" way of acting outwardly but inside everyone is still unique. (being different isn't the bad thing though, lying to yourself to "fit in" is)
133163
becasue some people may try to just please everybody and try to fit in with others, \nit's obvious that they are insecure and not comfortable being theirselves
1067889
Because people compartmentalize their lives. I do the God thing here, I act this way around those friends, I do these things around others. That's the way a lot of people are. Chameleon's  :)
1142277
Some people get insecure or fearful around others who are not like they are. They attack the one who is different, to help them feel better about themselves and their decisions (which actually probably means they are not secure in their own decision or choice).
1093648
They are afraid to upset you or make you feel bad.  They also probably heard gossip or wrong information about your breakdown.  The best thing to do is act like you usually do and they will stop acting weird after a while.
162472
Of course I do.It bugs me because there are some people that you could just be hanging out with and then they do something that is just horrid so they say sorry.  Then the same thing happens again.  Some time or another it just gets old and thats when i wonder why they just don't think before they act.    This doesn't mean that everyone doesnt think before they act it just means that sometimes people get a little carried away.
456367
TThe short answer: the irrational idea springing from the limbic system of all human brains...comes from our cave man days and shows up as irrational worldviews.
706780
Small steps, billions and billions of small steps . . . \nWe each prevent it when we behave as if each and every person we encounter is an individual (what a notion) and not belonging to a 'group' we perceive them from.
872048
Different people have different ambitions and they are not always in sync with that of organization, hence all these problems. Basically people are plain stupid, simple.
232615
Groups, by and large, are stupid.It's a herd mentality.Individuals can be intelligent.And there's certainly a shortage of those types!
722184
Because people voluntarily segregate themselves.
228012
Much like cats, people are quite resistant to any sort of rules or change that are being forced upon them; they react much better if they are gently led.\n\nSee his book "Managing People is Like Herding Cats"