Until he resigned as the head of the online home goods retailer Overstock on Thursday, Patrick Byrne may have been one of the most unusual CEOs in the United States. A libertarian proponent of blockchain who built the company almost from scratch, he gained a reputation as a conspiracy theorist and for strange behavior — including referring to a foe as a “Sith Lord.” Over the past few weeks, however, Byrne’s public conduct became even more bizarre.