> How would you know it is or is not luck?

It's hard to know in the moment, but almost every promising fund has subpar long term results. Whether they lost their touch or were lucky in the first place, it means that seeking out promising funds is a very bad way to find a place to put your money.

The number of funds with significant valuable insights is low, and the number where those insights are bigger than the fees is lower.

Anyway my point was just that a big spread of outcomes doesn't prove that significantly different skill levels exist.