Why is it hard to trust our instincts?

This is something I've been wanting to write about for a long time.  It is something that I found in the movie The Girl with the Dragon Tattoo.  The movie itself was an interesting, gripping watch, not to mention very violent as well, but this is about one specific scene in the movie.

This is towards the end of the movie in the scene in the basement with Mikael Blomkvist (played by Daniel Craig) suspended in chains and Martin Vanger (played by Stellan Skarsgard) about to kill him.  Martin says to him:

Let me ask you something. Why don't people trust their instincts? They sense something is wrong, someone is walking too close behind them. You knew something was wrong, but you came back into the house. Did I force you? Did I drag you in? No. All I had to do was offer you a drink. It's hard to believe that fear of a offending me is stronger than the fear of pain, but you know what? It is. And they always come willingly, and they sit there, they know its all over, just like you do.

These lines seemed very powerful and stuck with me.  Why?  I realize I often ignore my instincts and act in ways that might make me appear more socially acceptable.  In fact, I'm so used to burying my natural instincts that it is hard for me to even pinpoint what it is trying to tell me.  This is the kind of thing that leads to analysis-paralysis during decision making because the external parameters are often inadequate when capturing the effect of unknowns.

This quote from the movie did two things.  It articulated something which I felt has been true for me and also made me aware that it is probably not that uncommon.