Regardless of the possible "viable business opportunity", here is what I do not understand:

If the purpose is to attract new, possibly younger and affluent tourists. Then just jet skis are not the answer to the problem. People will not make a choice on a destination just because there is the availability of jet skis. I don't think I have ever heard of a person saying "I want to go to an island destination that has jet skis as the priorty".

They will ask about the availability of "water sports", but that will be far down the list from their primary requirements for a destination. To attract a new group of tourist you need more other capabilities (shopping, restaurants, hotels, villas, etc and even at a reasonable price). It is not like you are going to a destination to be on a jet ski 24/7 -- you are going to the destination for many other factors.

Without the other options in place there is no more of an incentive to choose Anguilla over the many choice already available. So jet skis alone will not drive new tourist to the island.

Will jet skis be rented if available? That answer is yes, without question. But if the question is: Will jet skis alone bring in a new set of tourists and their dollars, then that answer is no. All it will really do is move the money from one part of the tourist industry on the island to another part of the tourist industry on the island, so a net change of zero. If you think about it, even in your own situation, generally you have some sort of budget for your vacation. That budget is not going the change just because there are now jet skis available. So if the budget does not change, then there is no new money being spent, just a change on where it is being spent.

If the idea is to generate new tourist, then the other areas need to be looked and planned and build first.