The marijuana trade affects interstate commerce, just like the health insurance trade. That’s why Congress has the power to regulate both.
Sure, that’s why only marijuana that’s transported across state lines is illegal. Oh wait.
No, the Commerce Clause is why ALL marijuana is illegal, whether it crosses State lines or not. That’s the point. Under Gonzales v. Raich, even non-interstate commerce can be regulated under the Commerce Clause. And that make the Commerce Clause the bad mofo that it is. It’s a virtual catch-all for anything the Feds want to do.