Addiction is another case of extending the hell out of a disease.

If you haven't been to a bad area for a while go for a wander around skid row. That is mental illness and addiction.

Too much food, too much using the computer, too much porn, at worst bad habits unless you weight 1000lbs and got fired for jacking off at your desk.

Medical guilds like to turn things into diseases, that way they earn money "treating" them. This treatment usually involves getting you hooked on there drugs that drug industry sponsors can earn lots of money from.