It's because gambling is for fun, which is why people got addicted to it as a form of entertainment, but in trading, it is somewhat of a skill or a job that you are pushing yourself to do just to gain profit. Also, people really misconstrue trading as gambling, as others just treat it like gambling by guessing where the price goes and relying on luck, and that is where the big losses start. Though there are still people who are addicted to gambling, let's say their screen time is more than 8 hours, as they are really wanting to trade, which is also a bad thing because you'll be trading huge amounts at that time and again prone to losses.
Trading should not be a job, although it can be a job for those that understand it. Trading can worse than gambling for some people,, they will learn but still lacks the knowledge ti make profit with it. Fir anyone that is trading, it is good to first use small amount of money and continue with it. In trading, someone ncan be addicted and continue to trade and lose. I am not disputing what you said, bit trading is very risky like gambling.