If a system is good at predicting prices and makes you money, why sell it to others. It would be worth millions. The quant hedgefunds spend millions developing

If a system is good at predicting prices and makes you money, why sell it to others. It would be worth millions. The quant hedgefunds spend millions developing "black boxes" to carry out trades and guard the secrets within like it was their own life. And yet here we have these people giving it away or selling it for 2.99 on the Play store.