None of those seem to affect anyone else, so as long as the person experimenting on themselves is of sound mind I don't see the problem.
Not everyone wants to see someone die in a horrible way and have to clean up the mess.
No offense, but a misleading and inaccurate analogy. It's much closer to bans on chemical precursors of drugs like MDMA or LSD. Those chemical precursors have many legitimate uses, but since some people use them to make illegal drugs, normal citizens cannot acquire them easily, or without breaking the law.