A darkroom is kind of like a house or a boat - it's a hole in the ground/water that you pour money into. Unless you can offer a specialty service that people can't get elsewhere (say platinum printing or other alternative process support) it's highly unlikely that you can earn a living with a darkroom. Make some money? maybe. Maybe even make enough to clear a small profit after your expenses are recovered. Anything more than that is somewhere between flying pigs and frozen inferno.