This is known as the orthogonality thesis -- goals are orthogonal to intelligence. Intelligence is the ability to plan and act to achieve your goals, whatever they are. A stupid person can have a goal of helping others, and so can the smartest person on earth -- it's just that one is better. Likewise, a stupid person can have a goal of becoming wealthy, and so can a smart person. The smart person is Jeff Bezos or Bill Gates.

There are very smart people who put all their intelligence into collecting stamps, or making art, or acquiring heroin, or getting laid, or killing people with their bare hands or doing whatever they want to do. They want to do it because they want to. The goal is not smart or stupid, it just is. It may be different from your goal, and hard to understand. Now consider that an AI is not even human. Is it that much of a stretch to imagine that it has a goal as alien, or more, than the weirdest human goal you can think of?

*edit - as in this video: https://www.youtube.com/watch?v=hEUO6pjwFOo