[gruez]

>Even the Medallion Fund only averages 20-40% gains a year and they've stacked the deck with every possible advantage of resources and the most brilliant folks they can find.

The Medallion Fund is also larger than a single quant's trading portfolio. This is important because a given trading strategy loses its effectiveness (in percentage terms) when scaled up. A strategy that yields 100% return on a 10k investment is unlikely to return 100% on a $10M investment, for instance.