Torrents are very inconvenient compared to many streaming services.

Therefore, you would expect most people to opt for Netflix. (And by and large I'd expect Netflix to be more popular in mass than tormenting at this point for places where it's available.)

But what if it's not available where you live (That's inconvenient), doesn't have the content you want (That's inconvenient), or you want a file you can play offline that isn't allowed to be downloaded on the Netflix app?

Convenience wins almost every time, but not having the option to do something (be it for lack of $$$ or availability) isn't convenient so that's when more people turn to piracy.