A sensible, sober CEO would still need a lot of political capital to push back against a boardroom that's hounding them to jump on the latest hype train. You certainly won't get that from a CEO who just took that position a few months ago.
A sensible, sober boardroom that doesn't push their execs to jump on the hype train would need to answer to angry shareholders. It's almost certain that >50% will support the latest fad and would vote out a board that they perceive as being behind the times.
That's where startups and privately owned companies get their natural advantage of being able to go against the grain.