I do not know about envy. What I do know is that there are over 7 billion people on the planet and the difference between the rich and the poor is like this: According to CNBC http://www.cnbc.com/id/100780163, the top percent own 39 percent of the world's wealth. Seventy million people control 39 percent of the wealth. In addition, some of the companies make their profits by exploiting so many others.
Do not get me wrong there are some wonderful super rich people. But honestly how much does a person need to live in the world? Oh yeah, one more thing, think about all the unused resources that some of the super rich own just because they can.
If you get a chance read some of the economic reports about what is really going on in the world. I think you may get better insight into why it appears that the poor may envy the rich.