Disliked...
Well, first off, is the trading method they are using effective enough to produce more winning trades than losing ones? This point was also made by one or two other posters here. The only way to know how effective your method is (the ratio of wins to losses that your method produces) is to back test it. You need to convert your trading system into information (facts and figures) that your mind can use to beef up your emotional equity for trading.
...Ignored
Take a simple example 60% winners, average win 95, average loss 105 (Basically I'm using 100 but assuming 5 costs)
Expectancy is $15
So what do you expect after 10 trades? $150. But the standard deviation of this is $300. So 68% of the time you will get -150 to +450.
Go out to 100 trades - average $1500 but standard deviation is now $1000. So there is still around 5% chance of losing money over 100 trades.
So you have 2 problems. Firstly, you are inferring your statistics from a single instance of the past. Secondly when you actually trade your results will be markedly different your tests because of randomness.