To get reliable access you either need to convince an adult to give you access (which is always game over) or you need to engage in some kind of future planning, which is a similar skill set as the one necessary to notice that getting addicted to cancer thing might be a bad idea. Stealing uncle Roy's marlboro doesn't work because uncle Roy is generally then going to notice that they're going missing and either start securing them better or deduce where they're going and visit some punishment on the kid.