Fair view. A few points:

- Numerai does not have the ability itself, it harvests predictions from many others.

- To assume that better than random guessing is not possible, is to assume that the stock market is operating at maximum efficiency, and that all the hedge funds that are profitable have very lucky random number generators, instead of well-paid quants.

- The co-founder of perhaps the biggest money making hedge fund, Renaissance Technologies, has invested in Numerai. http://www.wsj.com/articles/renaissance-technologies-hedge-f...

It's a bit like saying you don't trust any SEO company that does not rank #1 for SEO. Fair, sure. But the reality is a bit more grey. Disclosure: Won a few bitcoin on Numerai.