I think I’m gonna have to read up a little more, but I’ve seen this in support of the excess returns view:

https://www.nytimes.com/2011/07/10/business/mutfund/congress...

And this in support that avg congressional portfolio is not performing well:

https://www.mit.edu/~jhainm/Paper/Eggmueller_CapitolLosses.p...

https://www.morningstar.com/news/marketwatch/2020041854/sena...

Looks like there might be a historical component around the STOCK act that different studies play with for their data window. In either case — I still say for the poor level of diversification within & around asset classes that I don’t see a lot of shining examples of how to achieve success.