Drugs:
-Achieve a state that can be cooped much better with spirituality.
-Becomes retarded for the duration.
-Addiction.
Insanity:
-Not negatively affected by stress, and lots of creepy pleasures.
-Intelligence is not restrained, and possibly enhancing strategic thinking.
-Can come up with out of the box idea.
-Able to ignore restrictions such as social status.
-No addiction. You are either insane or you are 'normal'.
-Morality is heavy hindered, but not to the same degree as those damn addicts.
When you came across a junkie, you know you can just ignore him. When you meet someone insane, you know you need to be careful.
Says you.
There are various chemicals you can take that enhance various types of cognition. See also nootropics.
Addiction does not always happen, and there is a distinction between chemical addiction and psychological one.
Insanity is a tricky term within psychology. To say that those afflicted with it are unaffected by stress is potentially so wrong it is quite hard to understate -- or if you prefer see why no loud noises, deviations from routines, extreme sensory input and more is often required for those not doing so well in the head. Creepy pleasures may well not be a pleasure at all either.
Even ignoring the somewhat contentious many types of intelligence thing if you are locked onto one particular item/concept you are typically not free to explore all you might explore.
Plenty of people come up with out of the box ideas with drugs and by not being constrained in other ways, up to and including ignorance.
Social status can be ignored by many.
One can get better from mental illness. Just like because you had a cold once does not mean you still do. Some don't get better but so many do that I find your notion that it is for life quite appalling actually.
Many people that use tobacco are heavily chemically addicted but seem to function just fine within society. Your thoughts there?
What if I meet an insane junkie? Likewise I have been attacked by junkies, insane people tend to only attack me if I go into secure wings of mental hospitals.