Do you like the "Pay it forward" (free college) idea?

When college is free to the student, they tend to do worse than the student that has to pay their own way. I believe a better idea would be reimbursement for good grades. If there was a 100% refund for an A, a 75% for a B, a 25% for a C, and everything else would be 0%, a student would study harder because it would be their money on the line and not someone else's.