Shawn, as a graduate student in astronomy, I get paid a monthly stipend to pay living expenses while I work toward my degree. This is enough to live on, but there definitely aren't any grad students living like kings! For most sciences, you can make a reasonable living, but you certainly don't go into a scientific field to get rich. Luckily, astronomy is one of the academic fields that do pay reasonably, so that most people who love it can choose it as a career without having to work a second job to pay bills.