Maybe getting caught causes the island to be shut out and papers automatically invalidated if there aren't sufficient real endorsers.

Unless you can be fooled into trusting a fake endorser, that island might just as well not exist.

> Unless you can be fooled into trusting a fake endorser

Wouldn’t most people subscribe to a default set of trusted citers?

If there's a default (I don't think there necessarily has to be one) there has to be somebody who decides what the default is. If most people trust them, that person is either very trustworthy or people just don't care very much.

> there has to be somebody who decides what the default is

Sure. This happens with ad blockers, for example. I imagine Elsevier or Wikipedia would wind up creating these lists. And then you’d have the same incentives as you have now for fooling that authority.

> or people just don't care very much

This is my hypothesis. If you’re an expert, you have your web of trust. If you’re not, it isn’t that hard to start from a source of repute.

A web of trust is transitive, meaning that the endorsers are known. It would be trivial to add negative weight to all endorsers of a known-fake paper, and only sightly less trivial to do the same for all endorsers of real papers artificially boosted by such a ring.