When you don't believe the company strategy will work (IFS), and all of the raises and 'rewards' are cancelled, but you need to make a living and the job market has gone stone cold... so you decide that you are going to only work just hard enough to not get fired.
You know this is unethical, but you view the world as inherently unfair. You grew up being told everyone is a winner and hard work doesn't matter. Everyone deserves an equal outcome.
If you know this is true but it makes you uncomfortable, think twice before hitting the thumbs down button.