Working a job doesn't necessarily mean your child won't get good grades. The idea that a parent wants to pay for their student's school so they can "focus on school" and get good grades is way oversold in my opinion.

They're college students, which means they're not going to be studying 18 hours a day. They're going to be spending lots of time doing things that college kids do, like having a social life, wasting time, doing stupid stuff because they're bored, and yes, occasionally studying. Kids who have jobs have to learn quickly how to manage time and study effectively so that they still have time to have a social life, waste time with friends, and do stupid stuff. Kids who have college paid for never really are forced to learn those skills.