I wonder if his friend traded one or more pairs? It's different when people make multiple trades at a time with the same pair, and when people diversify and get into multiple pairs.
I guess that risk and reward ratio explains everything. It doesn't matter if someone goes with one or more pairs, single or more trades, it's about control of risk reward ratio! Those who chase big profits will face higher risks and probably will lose most of the time... those who have control can have fun and harvest profit here and there, maybe nothing big but at least something will come.
Regardless of the number of markets being traded there should be some sort of limit to the number of positions which can be opened simultaneously, as the more positions are opened the higher the risk you are taking.
And as we know control over the risk we take is one of the most important abilities we may have as traders, while at the same time is the most unforgiving, as you could open your positions a little bit early or late and your system will still be profitable, but take too much risk and eventually you will bust your account for sure.