Okay this is kinda backwards. Alcohol is worse than nicotine. Nicotine withdrawal doesn't cause seizures or death. Nicotine is less destructive to an addict than alcohol is, although it's more addictive overall.

While cannabis and psychedelics should be legalized and can help many people they aren't without risks. They can cause temporary psychosis and permanent sensory abnormalities/minor hallucinations. In some cases they can trigger diseases like schizophrenia. It's all dependent on how your brain is wired and what happens when you are tripping/high.

There was actually an off-duty airline pilot that nearly caused a major accident when traveling in the cockpit jump seat after taking mushrooms a few days before hand. He jumped up atns tried to shut off the engines, and very nearly succeeded. There is a great mentor pilot video on it if you can find it. It's a great example of what can go wrong with psychedelic drugs. That man ended up in jail btw.