Some drugs, like opioids, create a physical addiction. Their body cannot function without the chemicals.

Saying "Stop taking the drug" to those people is equivalent to saying "Stop eating". The body cannot physically function then.

Nicotine is also a chemical that induces a physical addiction.

Surprisingly, THC (marijuana) does not, apparently... Someone can stop cold with no physical issues, only psychological ones.

Black & white thinking is easy. Nuance is hard though and might even lead to empathy.