As long as the car is running, it will not hurt anything to drive a car with a bad starter. However, you may end up stranded if you drive your car in this condition. Once you arrive at your destination, you will normally shut off the car. If you have a bad starter, then you might not be able to crank the car when you are ready to leave. With a bad starter, there are not many things that you can do to get the car running again. In some cases, you might be able to tap on the starter lightly with a hammer to get it working again, but you should not always count on that. For these reasons, you should go ahead and get the starter replaced as soon as possible.