In the Junior year, the PSAT exam counts as a qualifying exam for the National Merit Scholarship. You are only competing against other juniors in YOUR state. 8000 first-place winners are chosen as National Merit Scholars and the scholarship for that can be anywhere from $2500 to $100,000 depending on the college you choose to attend.
For Freshmen and Sophomores taking the PSAT for practice has been shown to increase the junior year scores by 15 points. So this is important.
If the parents work for any of the corporate sponsors there may be a scholarship available through the parent's employer for taking the exam and doing well. Generally, if this is the case, the corporation has an application that must be submitted MONTHS in advance of taking the exam, sometimes as early as winter of the sophomore year. Check the list: