The irrational and bonkers part is where that giant financial industry ceases to believe that it could be risky to lend boat money to a fisherman.

It's not necessarily irrational and bonkers for there to be more money changing hands in the fishing financial industry than among fishermen themselves. By itself, what does that really mean? It doesn't mean that money is being created out of thin air. People are making bets in that system, they are loaning money and taking specific complex risks, and as a result some people will lose everything. But also, some fishermen will be able to buy a boat or survive a season of poor catch, even in situations where many fishermen experience misfortune simultaneously.

The question is how it affects the community. Maybe there's a big crash and people in the island lose their livelihoods. Or maybe the very existence of their livelihoods is due to financial services that make the fishing industry large, robust, and prosperous.