Depending on how much awareness, control and vividness within the lucid dream, a lucid dream in a way is exactly like waking life. Though, I think a lucid dream is a amazing no matter on your amount of control. The only way I can see Lucid dreaming as an addiction is if that person isn't happy with their waking life and choose to live more so in their own reality ( their LD) then in reality. So the addiction would come in with the constantly sleeping trying to have a lucid dream so they can just stay there.