I'll go first:
Time Horizon. Hedge fund managers have to worry about their clients every month. You should be focusing on the next 20-30 years. That is a completely different sport that just happens to be using the same stadium.
Most institutional investors couldn't focus on the long term even if they wanted to. They have to be worried about what their competitors are doing now.
As a retail investor, you won't fire yourself because of a bad quarter. The biggest risk you face is losing money between now and when you need to use it. The biggest risk an institutional investor faces is losing money over the next quarter, maybe over this year.
(Data Source: Robert Shiller, 1-Day Returns Since 1930, Via S&P Capital IQ, Image source: Morgan Housel)
What edge do you think retail investors have over Wall Street?