[mft_]

> The ways in which Musk dug himself in when experts predicted this exact scenario confirmed to me he was not as smart as some people think he was.

History is replete with smart people making bad decisions. Someone can be exceptionally smart (in some domains) and have made a bad decision.

> He seemed to have drank his own koolaid back then.

Indeed; but he was on a run of success, based on repeatedly succeeding deliberately against established expertise, so I imagine that Koolaid was pretty compelling.