You're using the principle of the 3%: you cannot logically legislate against the 97% who will not be negatively impacted by something, in order to protect the 3% (such as those with schizophrenia) who will.

Otherwise, just for starters, we will have to ban alcohol and tobacco - oh, and don't forget kitchen knives (at least 3% of people guilty of violent crime have used these to commit the crime) and then of course there's the small matter of the large number of bad drivers on our roads - according to your logic, we'd better get rid of all cars too (because I can guarantee you bad driving sends more people to government hospitals (funded by your taxpayer  money) than all the marijuana in the world!!