I can direct you to the Atlas Society or the Prometheus Foundation for competitors of ARI. As for unrelated fields I imagine it's the result of her philosophy's impact allowing them to become experts in otherwise unrelated fields. The practical application of Philosophy.

> How come the only experts that defend Rand are associated with the Ayn Rand Institute or are experts in an unrelated field?

Can you explain how you went about determining that this proposition is actually true? Are you running an automated bot of some sort that crawls the internet looking for people defending Rand? If not, what methodology did you use?

And if you have no such methodology (and are therefore running on heuristics/faith perceived as facts), does it not seem a little ironic that you are criticizing the quality of other people's beliefs/cognitive abilities?