It doesn't really matter if the actual occurrence is vanishingly small, what matters is the differential between the consequence of buying the wetsuit and having a shark pass you over (a small number of dollars, hundreds at most), and losing a limb in a shark attack (natural limbs are irreplaceable, prostheses and medical costs will be in the tens of thousands of dollars). That seems like it would make sense for anyone who spends a non-trivial amount of time in the ocean. Most peoples' houses don't burn down, but most people still buy fire insurance.
