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The sharks do not see us as food, they are mostly curious about us.
Such diving has safety equipment to keep the sharks away if they threaten and the dive is done in groups to keep each other.

As a principle, a shark is not an animal that threatens humans.

As long if you don't threaten them or make any sudden moves they won't hurt you.

The only time it's dangerous is when the visibility is really bad and they can't see that your aren't food and at places where tourists cage dive with sharks (South Africa, New Zealand) and they feed them and make them more aggressive.