What is the problem with using bandwidth without permission?

What will be an ideal response?

Using bandwidth without permission may seem harmless, but what if accidental damage happens to a system or if alteration to processing information and codes occurs? If the network has been hacked, it doesn't much matter whether the hacker directly caused the error or mischief, they will be blamed for any loss or damage. In many states, unauthorized use of a computer system is a crime, in addition to being unethical.