What is it with...?

What is it with people who expect perfection from others when they themselves are as imperfect as any one human can get? What is is about people that when you first meet them they seem as cool as an icicle but then as you get to know them more they change and appear the total contrary of when you first met them?  What is it about people that they expect everyone to help them out when in trouble but when someone else is having problems are the first to turn away?  What is it about people that when they see people having a wonderful day feel the urge to go ruin it for them? I can keep going on and on for days jotting down these many things I notice in us humans.  Man is a very peculiar being.  Don't try to understand them.