The first time I pirated a game was when I was unable to play Mass Effect 2 due to DRM blocking my ability to play at all (highlighting the irony of DRM, the fact that the pirated version was free of this issue).
When I had a potato PC, I would often pirate games before I bought them, to see if they would be able to run. If I hadn't done that, I would have erred on the side of caution and not bought any games I was unsure of.
There are also a few pieces of media I've enjoyed that would have been literally impossible to access if I hadn't pirated them, and were impossible to pay for.
Piracy can also allow people to access games and/or software that would otherwise be lost to time (abandonware).
Not all piracy is stealing and also some stealing is based.