Yeah, most restaurant owners, regardless of the number of Michelin stars to their name, aren't rich at all. Nor are their top class chefs. You'd make more money working in IT and your hours are far less stressful.

If you want to make it big you need to treat it like a business, like Gordon Ramsay does. He owns 23 restaurants (maybe more) all over the world, his name is known by many, and the income from tv-shows would pay the bills by themselves; they also serve as advertisement for establishments with his name attached.

The few restaurant owners I know who make a good income here in Amsterdam tend to own more than 5 restaurants. Some have their own branding going on, some just take care of the business side of things. And even then I think it's a whole lot of work and stress for relatively little pay.