People playing in casinos, betting on sports and astrologers - they all believe they know ,,something''. It will take them years and it will cost them lot of money to find out if they really knew something.

If you compare a healer and a doctor you will see who knows something and who doesn't.

Imagine japanese value investors buying after market crash in 80's, they still didn't make a penny after 20 years.If the same thing happens in US all long only investors will be dead.

It's very simple if you really know ,,something'' you will start getting richer .

If there is a bull market and you are short only fund and you are beating the market heavily then you know something.
If there is a bear market and you are long only fund and you are beating the market heavily then you know something.

If you are small investor and you know something, you should have enourmous profits in comparison with big funds, that don't have so many opportunities.

It is the same with investing/trading strategies. 

The ability to beat the market is condition necessary, but NOT sufficient ! You have to beat the market by large margin to be able to make a living from it.

Check your bank account and you will see: if you really know ,,something'' and you are losing money then it is not worth much.

PS:I lose money on my account !