The fact that the wealthiest 10% own 90% of stocks does not mean the game is rigged. (I mean, that's sort of like saying the game is rigged because the rich people have all the money.) Anyone can purchase stocks and the SEC works hard to make sure that all market actors have access to the same information. Stocks are one of the least rigged games! Long success in stocks does require some knowledge about picking a company and some discipline, but so do lots of things.
Unless maybe "the game" is meaning a broader economic "game", which is (apparently) rigged because some people are (way) richer than others? You'd expect something like 80/20 just from a Pareto distribution, which if I understood the paper correctly, generally occurs whenever people have free choice. I guess one could required "not rigged" to provide equal outcomes, but since people have unequal ability, equal outcomes seems "rigged" to me, just in the other direction, of pulling down the highly skilled.
Unless maybe "the game" is meaning a broader economic "game", which is (apparently) rigged because some people are (way) richer than others? You'd expect something like 80/20 just from a Pareto distribution, which if I understood the paper correctly, generally occurs whenever people have free choice. I guess one could required "not rigged" to provide equal outcomes, but since people have unequal ability, equal outcomes seems "rigged" to me, just in the other direction, of pulling down the highly skilled.