They don't have to short term maximize. They can totally decide that they want to maximize their position 100 years from now by making less money crowding out competitors and all shareholders can do is sell the stock.

Heck, just yesterday, the Delaware courts ruled that it was okay for Jack Dorsey to spend $306MM of shareholder money so he could drink with Jay-Z. (It was to buy Tidal, but Tidal was obviously a bad purchase).