I'm not sure great fund managers exist at all. I'm sure you can find a few emphatically bad ones, I guess. For whatever rare managers who do well over long per

I'm not sure great fund managers exist at all. I'm sure you can find a few emphatically bad ones, I guess. For whatever rare managers who do well over long periods of time, why isn't that knowledge transferable? I can think of two possibilities: 1. They have had an incredible run of luck. When you have process with randomness baked in, and thousands of managers, someone is expected to beat the average 10 years in a row. 2. A well cultivated network of insider information, or other nefarious means. Madoff claims to have started his Ponzi scheme in the early 90's, and it took multiple decades for that to be uncovered. Similarly, Cornblum and Grmovsek took 14 years to be discovered.