How people deal with insecurity

Over the weekend, I talked with two people who were unnecessarily critical of others.  They focused on the negative: whose product wasn't working, whose company seems too niche, who was overly stressed.  They did this even for friends.  I found it strangely difficult to break away from the conversations while they were happening, but afterwards I felt a lot worse about life.

I mentioned it to a friend, and she said they may have been feeling insecure about their own life, and hence propping themselves up by lowering others.

I have huge respect for when people can admit their insecurities and state them openly without tearing down anyone else.  People at Minted are really good at doing this.  I am sometimes in awe of my colleagues' ability to do it.  It takes so much confidence.

I wonder why it is so hard to break away as the conversations are happening.  Even though i am steadily becoming demoralized, I can't seem to walk away.  Because I am used to people doing this, and it feels familiar?  Because it is like watching a train wreck and you cannot look away?