I would like to say that although it is jealousy there are other things going on here that sort of warrant this opinion if only slightly. For one there is the very cliche "Imbalance of the classes" trope. However cliche it is, it is still true, there is an imbalance of wealth here. The fact that this guy is/was head of a firm with $2 trillion in assets says a few things about that. As much as I can say that eventually I will become a successful individual, how many of us will start businesses that will be worth $2 trillion dollars?

This next two paragraphs will be me ranting about the government of various places. You have been warned.

I would also like to point out how the middle class is the bastard child of the lower class and the upper class. I am middle class so of course this is slightly/very biased but it's my opinion. The government keeps the lower class down but gives them things that make them feel equivalent to the middle class. I'm talking about Section 8 housing and other various government provided things. While these aren't bad, they allow people to game and cheat an otherwise okay system. The middle class is then jealous of the lower class for getting so many things that they work hard for, for free (or at least negligible costs). The middle class is also scared of the living conditions in poor neighborhoods and think to themselves (I don't want to have to be in an area like that) so the middle class works hard to avoid unwanted circumstances but are still angry at the lower class for getting so many "Freebies."

Now we move onto the relationship between the middle class and the upper class. The upper class is the goal of the middle class. People believe that will hard work they can make it into that next tier of wealth and have a nice retirement await them. While in some cases true, many people are stuck in the same rut at the end of their time in the workforce as when they started. Many are actually stuck working today because of the recession. Though it is over, things have gotten more expensive and so the cost of living has gone up. So when someone like Bill Gates throws all of his money at charities, the other upper class people may say "Oh that's a nice thought, I'll do the same" the middle class says "Screw that guy for having so much money to throw around" and they are jealous that someone so many social tiers above them exists in the world because they know that it is near impossible to scale the socio-economic ladder in these times. True rags to riches stories are non-existent in america as far as I can tell. You may point at some social media developers (Namely Zuckerburg) but they all had fairly wealthy parents who hired private tutors to teach them their skills. That is why everyone is jealous of the upper class. The way that society has been laid out ahead of us means that we cannot climb tiers at a time up the social ladder. We can however, fail miserably and fall all the way down it.

Tl;dr Because no one can actually climb up the social ladder, we are all jealous of those above us.