Isn't there also an additional misalignment caused by shareholders who hold shares only to speculate on the stock market? Those shareholders don't care about long-term goals of the company, but only about short-term stock performance they can use to jump sell their shares high, and then buy some other shares low.

Short term speculators have no direct influence on the management (other than through share price i.e. the money they promise to give to the long-term shareholders to sell their shares) because they don't hold the shares long enough to vote on the shareholder's meetings - the long- and mid-term shareholders can order the board on what the priority should be or replace the board if it's not aligned with these goals; and there's a class of activist investors who buy shares in order to do just that, to steer the company somewhere else - but in order to do that, you can't be a short-term speculator, you have to buy, vote and wait before selling.