I also see the following aspect as a potential motivation to buying vs. downloading, unfortunately:

In most Western countries, people are reluctant of torrenting. It has become a thriving business for lawyers, torrent monitoring companies etc. to pursue downloaders of copyrighted works, issue C&D letters and slap them with hefty fines (the reason being that while downloading something via a torrent, you simultaneously are uploading, therefore distributing files illegally).
However, if you buy a bootleg from someone, you revert all legal responsibility to the seller who is selling it to you.