Automated trading is mechanical trading and is very much like gambling. This in the way that you should try to become your own house. In order to do that, you need to follow your system without question, and that comes with its own pitfalls of being wrong even if the stats indicate you "should be right". Also, mechanical rules may make you miss better opportunities that the system just doesn't catch onto, so it may have worse performance than some form of discretionary trading. It's very hard to make steady returns using mechanical rules, as markets ebb and flow, so may drawdown and pnl.