I agree.
Trading with big amount or what you can't afford to lose without the required knowledge/experience is basically gambling. Same as other bettings, like betting in skill-based games, sport betting, poker, politics, etc.
I believe a good poker player for example could win consistently with his/her skills. The good and successful ones are probably few
Maybe, if we continue to believe this way, we might find it as misleading to classify trading as gambling, as it is more over falls as an investment rather than gambling. Because for me, gambling is when you don't have the feeling of winning with more than 50% but you continue to believe and test your luck until you made it. In comparison to trading which is to continue studying and looking at patterns to make sure that you have more than 50% of chance to earn profit. In addition, you also watch the market that gives you more probability to earn.