I agree with that last part, about alcohol and nicotine, but from firsthand experience the nonsense about marijuana not being addictive is just dumb. Marijuana is not exactly physically addictive, but it clearly is mentally addictive. Every person I know who has ever had to stop consuming marijuana for more than a few days, agrees that they felt mental withdrawal symptoms. Plenty of biological and psychiatric studies show the same thing.
I recently quit drinking alcohol, after consuming it for nearly 20 years, on a daily basis. Alcohol is right up there with nicotine, heroin and meth, with regard to the most addictive substances known to man. The fact that marijuana is illegal and alcohol is legal is absurd.