Human tendency

Well like the title of your post, it really is human tendency. We tend to see what is lacking or what is abundant in us whether it's material or non material things. In result, we also compare with others what is abundant or not in them. This maybe a good or bad thing since it becomes a motivation on what we do in life later on.

so that most people would know what to offer for whom economically, and there are also rich guys who doesn't want to be with poor guys as they see them as trash of the society, i feel bad for poor people as all human SHOULD HAVE EQUAL RIGHTS

I think most of the people have the bad habit of distinguishing between the poor and the rich and I believe they do so as they can then compare them with themselves and can treat them accordingly.