Compare Spice to hard drugs in terms of their addictive nature and the consequences they lead to.
Spice will never be the same problem as hard drugs (Coke, Heroin, Meth).  Existing hard drugs turn people into crack heads and junkies for many years, maybe even a decade before they die or get clean.  Spice kills it's users quickly, this Spice epidemic will be over in a couple years, people stupid enough to use it will die.