Any other financial instrument or trading FX ought to be considered gambling when you don't understand what you're doing.
When you understand what you're doing, it's about how much risk you're ready to take to achieve the outcomes you desire. Whether, you're willing to only risk 30 pips or 100 pips, comes down to the individual trader and their individual trading program. Assessing risk is a lot different than gambling and if you don't understand how to quantify risk, you have no business trading.
A roulette table is a game of chance, where expertise can't automatically change your chances (that is pure gaming )....trading isn't purely an undertaking of opportunity because more experienced traders armed w/ technical knowledge tend to be more effective over time. I think that is a contrast.