Hypocrite/Complex?

I am beginning to dread seeing and knowing people who are hypocrites..I mean, one moment they are nice to you, and the next moment, they treat u like complete strangers. Are these people hypocrites? Or they are just a little more complex than me, thus I am not able to fathom what are on their minds? I do not know, and do not think I want to make an effort to be nice to them anymore....anyway, it doesnt pay to be kind..right?
I guess, this time, I really need an avenue to release that little bit of "air" within me....
So what is my lesson learnt? To be more vigilant in dealing with people.....not everyone is ur friend.....u know.