In some countries (Germany) using public torrent trackers (like what popcorntime is doing behind the scenes) will result in 300+ Euros of fines pretty quickly. You also have to factor the legality in which is a pretty big factor for choosing to pay on top of convenience I‘d guess.

Now you also have to explain your non-technical guest how to use a VPN, pay for it and make sure it’s always running before starting popcorntime.

i just set it up in the router, all they do is connect to wifi and follow a link. i do it for personal home movies but you could extend the concept trivially for sharing a home library of copyrighted torrented movies