Compound growth is also the exact thing that is being criticized here. Your wealth grows simply by virtue of ownership. No labor needs to be performed. When somebody says that you can't earn a billion dollars they are the same thing that PG is saying, he just doesn't think it is bad: the way to become a billionaire is to own things whose value rises over time. The issue is whether this can be meaningfully called "earning" it.
Are you doing something to create that value? If yes, then I think you are earning it. If you are simply an investor, then no, but we need investors to make the whole system work.
we only really “need” investors because of the structure of our economic system. we need humans to do stuff regardless of the system.
worth mentioning that our current system is setup by and for the people who own the stuff so its no surprise that we need them to make new stuff.
Using your own logic, if we need investors to make the whole thing work, then an investor playing their role has obviously earned their take. If they didn't exist, many things would simply never have been created.