Sleeping pill addiction is very serious - and an addiction full stop. Whether he was desperate for the stuff to help him sleep or get high, the fact is that he was dependent on it, which means he was addicted. Doesn't matter the reasons - addiction is addiction.
You seem to have a very skewed idea of drug addiction and that one can only be addicted if they are a junkie rifling through bins for a fix. Addiction has many guises and MJ was a hopeless addict.
Propofol is not a sleeping pill and is not known to have the addictive potential of typical sleeping pills such as benzodiazepines