The victims of hacking spend sleepless nights away from their families working hard to see if their computer systems have been damaged by intruders. They worry about it. If there has been damage, it can cost lot of money to fix the data and the programs. This money lowers profits for companies or increases costs for nonprofit organizations. Organizations are made of real people.
Real people lose because of criminal hacking.
On another level, some people get caught when they hack, and their reputation for dishonesty can follow them for many years. I have met young people who didn't think they were doing anything wrong but who discovered how hard it is to be accepted at universities were to get good jobs when they have shown themselves to be sneaky criminals who obviously did not care about the people that they hurt. If these people continue hacking past their eighteenth birthday, they can go to jail for unauthorized access to some kinds of computers. There are many ways to learn about computing. It is not necessary to become a criminal in order to learn.