Although it should not be your primary motivation, asking questions will typically add to your participation grade for a class.
Frequently, teachers seek ways to improve their courses. Asking questions will help them better understand how their course materials and lectures are understood by the class. They can then adjust their lectures to explain concepts more clearly and draw more relevant connections for students. Additionally, you may have information to add to the lecture based on your own experiences, which the instructor may not have encountered or considered before. Your questions and contributions can help shape the course in the future.