When you apply for grants for college students, you will be asked to provide a transcript of your grades so far. If you are failing your classes, the people who are handing out the money will want to give it to someone else. They do not want to pay for you to fail, after all, when the money could be spent on someone who will excel. You need to keep your grades up as high as you can. This will make you money because it will make it so that you are eligible for grants that you could not have gotten otherwise.