Why do we hate thieves (the non-violent petty theft kind, especially pickpockets) sooo much?

Thieves take what is not there's. In other words they have the audacity to take something that someone else worked hard for and they themselves did nothing to earn it. Why does a thief think it is okay to take from a rich man b/c he is rich. Even though the rich man worked his tale off to get what he has, sometimes. Thieves should work themselves and buy their own stuff.