It's not only about deaths. Injuries (I imagine many are life changing) are important also.

But then I don't think there are that many injuries from shark attacks either.

So what's the point? It's the perceived feeling of safety. People are irrational when they evaluate risks like shark attacks, and for this reason there will be a big market for this even though the risk it mitigates is relatively small.

On the other hand, it might even increase deaths/injuries from sharks as people feel invincible and get closer and more irritating to sharks - moral hazard.

Anyway, just some thoughts typed out as they came to my mind.