While I get your frustration, the root cause of the issue is not shareholder value maximisation, it's the failure modes of the free market.

Monopolies, lack of transparency, lack of competition, regulatory capture, failure to price in externalities are what allows this to happen.

And these failure modes are allowed to persist due to lobbying, normalised corruption, and the desire for a small/weak government.

The latter is useful for corporations, as it limits regulation, which is the main way these failure modes are supposed to be managed. Yes, too much/bad regulation is detrimental, but so is no/weak regulation.

The more baffling thing is that the modal American voter supports lax regulation and pro-corporate rules at their own personal expense.