I've heard of people implanting tiny rare earth magnets in their fingers so they can sense current flowing through wires and magnetic fields. I would like to try it when I can be certain they won't break when they're under my skin...:P
I think you may have mistaken N2O (Laughing Gas - Nitrous Oxide) and NO2 (Nitrogen Dioxide). N2O is a colourless, sweet smelling anaesthetic gas whilst NO2 is a toxic brown gas that is often present in exausts. Two very different compounds indeed...
The reason you fail to understand is because your lack of experience!
People have bad relationships, but they don't quit dating.
Some crash their cars when they're young but carry on driving, etc.
One experience isn't enough to simply write the whole thing off, and besides; the dentists practice probably isn't the best environment for mind expansion:D
Or they could switch to stimulants and empathogens instead? Imagine a scientist mashed on amphetamines and mdma, working throughout the night, with a smile on his face and beautifully pristine lab of course...:D