> You're obliged to maximize their earnings.

You're not though, legally anyway. Courts will generally not second-guess a board's business decisions so long as the board acted in "good faith" even if that decision results in loss for shareholders, or does something that does not maximize their returns.

Board just has to link the decision and the long term health of the company. But it's just that, health of the company which is legally distinct from the health or short-term desires of individual shareholders and investors.