What causes people to be snob?

have you ever expected someone to always greet you or talk to you on the streets? of course not.at times we expect someone that we now gives us their time but they don't, same as us ,there are times that we can't give time to people whom we know as often as they expect us to be.it is just our expectation of someone.and with concern to a "double-faced hospitality", it's the same, our over expectation of people.each person has their way of living their lives just like you and me who very different as to how we go about with our social lives.

I am not a snob and I don't care to be around them. I think that snobs are people who do not feel good about themselves, but try to make people think that they have it all together. But instead they go over board to try to compensate for their feelings of less than and end up coming across like jerks.