Even the bottom 20% that everyone is so concerned about in the western world are better off than any time in history - heck, I have no qualms saying I'd rather be bottom 20% today than top 1% just 200 years ago. That is the level of productivity we've had, and primarily thanks to our economic system.
Could it use some tweaks? Sure, if you want to advocate free healthcare or college, go for it, but the main concepts are still quite good.