the same way you do not work for free, everyone here in this world need to be payed if they run a service
also giving money for free would require continuous printing, because there will no more deterrent to how much it will be asked by anyone
Difference here is that there is no choice given.
Banks print every penny in the world. It means they get interests on every penny in the world. Interests that can be paid only by printing more money that they lend again.
That's why the statement "the world is 300billions in debt" is true. And it's in debt to the banks, not to the moon.