Yep this is the craziest part. The answer has been known for a long time. S&P500. Literally that simple
In the fictional world of Economics, humans are all homo rationalens, and never make such mistakes.*
Vs. in the real world...
*Yes, I sometimes wonder if there's a brutally predatory subtext here - with Economics quietly endorsing "do unto them as you will" maltreatment of anyone who the 0.01% can maneuver into behaving "irrationally".