Well, if you take the random-chance/selection-bias as the core of a snowball and add to it the various mechanisms which mean that the game of asset management is rigged in favour of the manager, then I think there is something to this. For example, asset managers get a part of their income from a MANAGEMENT fee which is a percentage of the assets under management, that they collect regardless of whether the fund actually does well. If you get a few bets right, make a name for yourself, more people will be putting money into your funds, and it all turns into a self-fulfilling prophecy.