It's not to motivate a particular person to deliver more, it's to ensure that you're able to hire that person - if they would pay, for example, $2million, then no one with experience at managing decent size tech companies would apply as they can get a much better offer elsewhere.

Also, CEO compensation is effectively between the shareholders and the CEO - if the CEO is making the shareholders happy and they want to gift him $200m for no good reason, well, it's their right to do so, it's their money to spend or waste as they wish, not the employee's.