I will say that is partially true I got about 20% of forex trader are winners because they have discover trading robot that they use in trading robot is it prevent them from getting into loss.Personally I don't think the 20% is overrated or exergerated because if like less than 20% makes it in forex , I don't think forex will be in trend as it is currently. In my opinion I could say up to 30% still makes it forex , the secret is just access to information before taking decision.