I think it based on people knowledge how deeply they know, what is the potential of that pick so that it can be better than gambling in long term, in that kind of case trading can't be consider as gambling when it has very good safety for some experienced people.
Yes, Gambling is purely luck and you have no control on it. While Trading requires good experience and good traders never lose. We cant say same about gambling as experience does not count much in gambling.
you can say that for gambling as general but that is not true at all for trading because you can never give a general rule that applies to everybody in trading.
there are a lot of users here that are treating trading similar to gambling meaning they buy a coin and gamble if it goes up or down and they have no idea why they bought that coin.