The Tenth Commandment is one of the most important economic lessons. The lesson is not that you should not desire more and work hard for those things; you clearly should. The lesson here is that should not resent what your neighbor has. If they have a car, you can clearly want a car also, however this is about you thinking that you deserve their car more then your neighbor does.
Liberals clearly have issues with the rich having so much. They not only want stuff, they think it is unfair that the rich have so much and that they deserve the riches' stuff. They are not happy with just earning their own stuff, they must have the rich's stuff.