This begs the question: If a drug has no pain for indulgence, and you can turn off the effect almost immediately with a counter-acting dose... Does it matter if you're addicted to it? Do we have a problem with people using drugs of their own free will if those drugs have no negative impact on their lives?
It is that last line that is the problem... Addiction does have a negative impact. That is the defining characteristic. Some examples here... http://listverse.com/2010/11/07/top-10-cases-of-extreme-game-addiction/