But if piracy would go away, then it would mean we live in a great world:
Software: FOSS/Freeware/Donationware software prevails. People want to use this kind of software, and this is the go-to for any appliance. People would be deeply affected if they could not use free (as both in freedom and/or money, as mentioned before) software - gone will be the days of everyone needing Adobe products or MS Office for their professional work, and the year of the Linux desktop would be in the history books.
Movies and TV shows: They would be available anywhere, on demand, in any format. Or there would be this website where you would go to and watch whatever you would, without ads. It would kinda be the same with music.
p0rn: I don't have enough knowledge in this field, I just go to certain websites when I need. Guess it would be like on the previous point? idk.
As long as those points are not achieved, there will always be a need for piracy, and people will always find new ways to get their content. So far, I do not see us being somewhere even close to that ideal world, so there are plenty of reasons for piracy to exist.
I personally try to pirate things more ethically, for example I try to buy music and games whenever I can, but I know several people that pirate stuff just because they can.