There goes the 'all you can eat' shrimp!
I can run to the grocery store and buy a 2 pound bag of mediocre frozen shrimp for $7.
Spend another $0.25 on fat, salt and some herbs, and I can turn that into a dish that will stuff three average people to the gills for less than $2.50 each. Granted, there are competitive eaters (who don't eat like that unless they're trying to win a contest), and the morbidly-obese who can put down considerably more than a pound of food at a sitting.
But thanks to the economy of scale, restaurants pay pennies-on-the-dollar compared to supermarket shoppers. AND there are sales in the restaurant world, same as the supermarket.
"Hey, do you think you can take 2,000 pounds of ground beef off our hands? $2.50 a pound if you do."
"Sure, ship it. I can sell that in a week. "
It works the same way as it does in the supermarkets -- brisket goes on sale after St. Pat's; beef flap goes on sale on May 8th or so; crab goes on sale in January (overage -- super high quality) and September (freezer burnt -- don't buy September Alaskan crab. It's been sitting for months.) Hot dogs are basically free starting July 6.
And there are ALWAYS vast quantities of shrimp that need to get turned around. Trivia question: Who consumes more shrimp? a) the city of Las Vegas? or b) the rest of the United States?
Endless shrimp didn't kill Red Lobster. Losing money selling shrimp is like losing money owning a casino. It takes a special kind of person to accomplish that.