In both meat eating and driving those activities have inherent harm, eating meat will cause animals harm, driving a car will cause pollution and release of GHG.
The harm of the drugs trade (on a societal level) is _due to its illegality_ I.e. it is run by criminals.
Regardless, it is absolutely not immoral or unethical to consume drugs. What is immoral, is imposing the negative consequences of prohibition upon society because of your particular moral code. You want to lock people in a cage at the end of a gun because you disagree with the choices they make for their own bodies. It is authoritarian shite of the highest degree.