I am currently reading this book. It's quite a heavy topic so this video was good Buttress to the book. As Sal said correlation is not causation, however neither capitalism or socialism have been able to provide an ultimate answer to question on inequality. The problem with socialism is that the Govt may use it as a proxy to expand its remit, which would further accentuate the problem. A Global wealth tax however is due on super rich without option for safe havens. Becoming Rich shouldn't be disincentivized, however becoming Super Rich is more a matter of luck than labour, thus they should be taxed higher than others
