For example, I know 3 traders personally who make a living with the profit of the forex trading. The long term spot forex market traders analyze the macroeconomic trends and join before anyone else. There is an edge on long term-swing trading, what about the gambling?
Are you sure that they are "traders"? Not investors? Or people which selling their "insides" to others?

I think they should be called investors as for living in long-term trading. Traders aren't living in the concept of long-term since they are continuously tracking the stocks and holding it for a short period of time. Buy and hold principle is for investors.
I do not think that gambling is like trading, sure they are similar with risk but that is the only similarities they have, the big difference is that day trading has a return of investment while gambling obviously do not have.
yes of course gambling is very different from trading, when you trade and the price falls then the only change is the estimated value of your assets whose value can recover when the price has recovered, whereas if you gamble and you lose then your assets will not be able to return again because the armpit is gone it will forever be gone.
In trading, the losses should be smaller than wins like in gambling but there is a difference: Traders can use stop loss and limit orders for managing the risk/reward. Gamblers are emotional which makes them weak, traders don't need to make an instant decision because the trading position can go back to the green zone after staying in the red zone for a long time.
Yes, in gambling if you lose, it's very huge depends on the amount you bet. While in trading, there are loses but minimal only since it requires timing to avoid huge income loss.