For some people, drugs are just another enjoyable part of life, not an escape from life.
Basically, an "I don't care anymore so just keep them banned" attitude or an inability to do analytical thinking to see that the negatives of our drug culture aren't inherent to drug use.
But for the other people, the ones not included in your 'some' I believe that drugs are used as an escape. I've known plenty of people that had their nirvana moment and then continued to use for years after because it's better than coming home and watching tv while waiting to go to sleep and start the 8-5 all over again. Walk into a gas station at 5 pm and see how many people buy a six pack on their way home. Or ponder the large amount of the population taking the legal drugs to alleviate depression.
You know, any way of living which can't be passed to other people is kinda useless.