I don't mean just seeing something nice and wanting to have something like that. Some people would not mind doing anything to take what belongs to another. Why do we have people like that?
I believe it's actually because of greed, there are some who want what others have, not because they don't have it but because they are greedy and want more of it.
It may also be causef by jealousy, low self-esteem and not being contented with what one have.