Consistent earnings can only be achieved through proper risk management. Even then, not every trade is successful. Anyone who is successful in every trade is lying. No exception. However, I currently have a high success rate. 

If you bring me a system that guarantees me 1% profit every day, I can tell you that I can find a customer who will pay $1 billion for it in a short period of time. From this statement, you can understand how important these underestimated rates are. 

Check "Dimishing returns".