If automatic trading really works why isn't everybody a millionaire ?
The reasons for this are many;
1) Traditionally strategies for automated trading need to be programmed, few are programmers, and have the time - it takes a professional team 3 months to develop a small set of strategies, having a trading idea from a professional trader !
2) The development platforms and that you have to program sets a limit to which kind of complexity, sophistication, and the count of different strategies you can develop.
3) There is in general no difference between a trading idea for discretionary and for automated trading - a computer is not a magic stick, the automated strategy still need to be based on a trading idea.
4) In general 99% of all strategies works till they do not work any more, works in the market behaviour it was tested to work in - in general till the market behaviour change against the strategy.
5) The market behaviour now change faster than strategies can be developed, mainly due to the increasing use of automated trading.
The above shows why we are not all millionaires, and also why the use of automated trading signals has been replaced by social trading in the retail segment, its too difficult to develop strategies (by programming) and there is a lack of strategies in the market.
However, automated trading and computer assisted trading is the future, proper development tools are not in the retail market yet, but they will for sure be.