Besides the wealth of extremely addictive substances (and activities) that are legal (some regulated), there's also at least one illegal drug that you're never going to be (chemically) addicted to: LSD.
The "we're protecting you" logic behind making arbitrary drugs illegal is nonsense. It's even more weakened by the fact that at least a few of the illegal drugs with "no medical purpose" have, in fact, some medicinal use: Marijuana for anti-nauseau, combating eating disorders, and pain relief, and MDMA for PTSD.