Then, by the same logic:
If all those serial killers were pot tobacco users, then all those specific pot tobacco users were serial killers.
Ergo tobacco likewise produces serial killers, and ergo tobacco should likewise be illegalized.
Q.E.D.
If you like, you can also substitute "milk" for "tobacco."
Regards,
Ah, I see you are familiar with the commutative properties of addition! Good for you!
Did you have some other point that you were trying to make? I'm not seeing it.