It's sort of hard to believe actually. I mean, any buffet I've been to, with the exception of Chinese, has salads. Who could eat a big salad (which they should have done) along with that much beef? Kind of sounds like they went there with the attitude that they'd show them.
I do think it's abuse of the buffet too, but most buffets are traditionally all you can eat, so they should have posted a maximum number of servings of the beef if they only had so much.
Either way, how humiliating.