Trading is more risky because you cannot know everything happening in the market. Skill gambling like poker you know everything before taking a decision and this is less risky. They are both risky and they are not recommended. Usually people who play skill gambling have less losses than the other ones.
I think you are only one person who said that trading is more risky than gambling. Because in my thinking, gambling is more risky than trading. No doubt, every business has take risk, but in gambling i couldn't see high risk. In one bet, we could lose everything and in one bet we earn jackpot. It is depend on our luck and not everyone is lucky one is here.
But about the OP, trading is risky, but if you know how to trade and use your skills, than we could earn more in trading than gambling.