IMO gambling is gambling as long as it's purely depending on luck and no support for it on other aspects "knowing methods of trading, best methods and ways to earn, specific market analysis", if the trader doesn't know these then it's merely gambling.
Well, there are 'gambling' like sports betting that is not purely dependent on luck all the time (I mean to say here, some time sports betting also requires some luck to secure profits). Most of the time usually sport betting dependent on your betting skills and just how much information you can get on the bets. So, I certainly believe trading always does not behave same as gambling. There are lot of factors to differentiate both.
i believe gambling is what you can not predict, so trading is not gambling but it is not as long as "you" can predict things but for some people who lack this ability it becomes more than a gamble to try trading. and the same thing is true about sports betting. if you can predict the result of the match it is less of a gamble.