I mean, define “well executed”. Theranos, in particular, it’s notable that very little of their money came from _conventional_ sources (traditional VCs, sovereign wealth funds etc). It was largely, essentially, _personal_ investment by stupid rich people; often via a family office, but ultimately at the direction of the stupid rich person. IIRC one attempt by Theranos to get investment from a real VC collapsed because they _could not provide audited accounts_. Like, they didn’t even have a fake set, they were not providing them to their investors _at all_.

I don’t think that any of the named ones were particularly well-executed, and people were trying to warn that all of them were problems for a while. Madoff might be the closest, but even there it was verging on being an open secret that there was something up; again, Madoff’s investors were not actually that sophisticated.