People don't understand how Ethics works.
On the anti-piracy side there are two groups: The first are artists who believe, without any evidence, that they can make more money when copyright is enforced.
The second are people start out assuming that the right to control information is a moral right. They then derive the ethical implication that people shouldn't pirate.
On the pro-file sharing side there are two groups. The first are libertarian-inclined utilitarians, which require people to prove actual harm before something should be outlawed or have tried to start a tech company and been threatened with a patent lawsuit. Every piece of evidence not created by the middle-man industry I've ever seen has supported their position.
The second are people who oppose the idea of "intellectual property", starting from moral principles such as freedom of expression, utility maximization or historic precedent.
There is no need to come up with anything new to say: the conclusion one comes to depends on what principles one uses to derive ethical implications. Intellectual property is morally wrong, declares one side. Intellectual property is a moral imperative, declares the other. It is impossible for either to convince the other, since neither is basing their arguments on a rational basis where facts or evidence might play a role.
Anyone who might be convinced doesn't care, probably because they are just ignoring stupid laws anyway.