> Yes, they need to look out for their shareholders but they also need to do right by the company, and companies can be formed for any legal purpose and everyone (the company and the shareholders) values things differently
The board has a lot of leeway into how they achieve profit for the shareholders, but all decisions they make must be nominally in the interest of that goal (assuming we're discussing a for-profit company such as Twitter). They can basically claim anything they do is done in the interest of shareholder value and be safe, but if they said "we know the company will lose money on this, but we really like X so we'll spend company money on it", they would pretty clearly be in breach of their fiduciary duty.