Part of it is that we seem to be wired to see things in groups, but it's also difficult to speak at the required level of specificity... let alone create catchy protest slogans!
I think anyone would be hard-pressed to come up with a chant to encompass your entire list!
Politicians
Companies Who Bribe.
Lawyers Who Litigate People and Business Into Bankruptcy.
People in Government Who Take Bribes.
People Who Can Work but Choose Not to and Rely on the State.
Slum Lords
Students Who Attack the Wrong Groups Based on Lies They Accept as Truth.
People Who Follow What the Media Tells Them.
In reality though people on the left don't have a problem with "the rich." The 99% group sprang up specifically in response to the double-dealing behavior of Wall Street that led to the 2008 crash. Sure they chanted against the 1%, but they did it in front of the people who had actually caused so much harm.
Meanwhile people on the left celebrate actual visionaries like Elon Musk, Bill Gates and Steve Jobs. People who have created new technologies we use every day and actually built their business. Personally I put them in an entirely separate category than the people who run the mega-corps of the world because those were all built by other people. The current CEO of Ford, for instance, probably earns proportionally more than Henry Ford did all for stepping into a pre-built company and keeping it doing the same thing day-to-day.
So all that said, I have to be pedantic and point out that the Pareto Principle doesn't mean what you think it does. It means 80% of the results come from 20% of the work...