Luck is never going to take you anywhere as far as trading is concerned. It all depends on your trading knowledge, experience and how well you apply them. We must not depend on our luck but dedicate ourselves to learn how to trade accordingly and be disciplined with it.
I truly believe luck does not have that much to do with Forex trading. It mainly depends on our skill, discipline, and patience. Not being a genuine trader, someone may make profit from 2/3 trades, but at the end of the day, he will lose them all. If you want to call those 2/3 profit trades by luck, you are right. Do not forget the end result though, where he would lose all of it.