Sharks are slow and cumbersome. Sharks appeared in the oceans after the dinosaurs. That makes them twice as old as dinosaurs and 100 times older than humans. Sharks have been feared by most cultures. In Hawaii, human sacrifices were chopped up and fed to the shark gods.
Sharks are picky eaters.
The tiger shark, especially, isn't particular about what it eats at all. The largest shark is the Great White Shark. The Great White, at 6.6 metres long, is a midget compared to the Whale Shark which can grow to 20 metres. It's not only the largest shark, but also the largest fish in the sea. All sharks eat fish.