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Making a profitable robot is a real big and very very long journey, but it is possible. There is a high probability to find scams because making a profitable strategy requires an enormous effort and amount of work and backtesting and simulation, to understand the key concepts.
In my opinion, one of the (obvious) "secret" is to build it in such a way to allow very large profit, which can compensate the inevitable losses that you have sometimes.
This clearly requires to have a good amount of money on one, or better, multiple account.
If you trade with too little money, you will lose all of it ;-)
In case, it's better to join some friend and share (possible) profits...