It’s more complicated than just one law that says “you must be a bastard” I admit, but fiduciary responsibility is a core requirement of any publicly traded company and very much is legally enforceable (this parenthetical aside stands in for about three pages of niche caveats and overly wordy exceptions that I’m just going to shamelessly handwave away). At best a CEO might be found to be civilly liable, but peasants non-C-suite employees are criminally charged for neglecting their fiduciary duty every day in the US.
Absolutely, but fiduciary responsibility, has never and was never intended to mean absolutely maximizing profits and especially at the long term expense.
That was a twisted idea that was put forward in the late 70s early 80s as a means to justify destroying companies for short term gain.