Except that it heavily contributes to supporting foolish policies and the bliss quickly wears off and requires ever increasing amount of ignorance to achieve the same bliss … see today's policies for reference.
I.e. ignorance of the drug underworld vs social ignorance of policy makers
To get "true" knowledge (lack of ignorance) on the suffering of drug abuse, one must experience it in some way, so avoiding this experience is the "ignorance" that leads to the "bliss"
Or at least that is my interpretation of the saying :)
