There have been a few attempts at "all you can eat" restaurants in my town. I went once with some friends to one of them an ate 8 pizzas for 9€ aprox. And that's what I ate, A friend ate a whole tray of shrimp(23€/kg) and small lobsters(15€/kg) and the others did not fall behind. I guess the idea was to make a profit from the drinks(under 15c/unit provider to 2€/unit customer). It did not go well

The one that lasted the longest as such closed after 4 months, the rest reinvented themselves as "all you can eat" one day a week from 8AM-11AM and normal restaurant/buffet the rest of the time or similar patterns.
The closest one I know of is 1 hour in car away if you take the highway, 3 hours through the old road, which in Europe's distance is VERY FAR AWAY.