But there are certain substances in drugs and tobacco that induce addiction. It's a bit different from some random loser who has no life and is addicted to an online forum or whatever; the online forum doesn't per se invite you to become addicted. I get your point but I think addictive substances are slightly different than computer games/sex/MTF/etc.
Psychological addiction is much worse than physical addiction. Your organism stops craving nicotine a few days after you quit and yet many smokers start smoking weeks/months after quitting. They don't *need* nicotine, but they crave for ciggies anyway.
Like Brotree already explained, one does not specifically need a drug to be considered an addict . There were cases where people killed each other in real life over virtual MMO items in games. Any addiction is harmful, even if you happened to be addicted to drinking 20 litres of water a day, eventually your kidneys would give out.
I am actually one of those people who would favor to legalize ALL drugs, but sadly fools need to be protected from themselves, so they need to remain illegal just because of that. Few bad apples ruin it for the rest of us, unfortunately. Be it a teen getting hammered and committing crimes or someone just chilling smoking weed all day, living off wellfare etc.
There are talks of controlling sugar in Australia just like cigs/alcohol. Why? Because people can't control themselves.