Hi Hellmark. Welcome on board.
The points you make are reasonable, but have already been addressed in the preceding posts or are (the way I see things) non-issues. I'll try to explain... after all this thread is clearly on the tl;dr side! :-)
About the "they copied the contents of my pendrive" scenario: this is the non-issue.
In my proposal, you get freedom in exchange for responsibility. Freedom to own your files and do whatever you want with them, in exchange for the responsibility of being careful about who gets them. So if you don't trust the people around you (other students, coworkers, ...) you should simply not leave your media files around, or encrypt/password protect them.
I introduced the "report theft to police" clause to cover the cases when you take all the reasonable precautions, but your files get in the wrong hands all the same. Say, because someone stole a piece of hardware of yours.
If something like that occurs, you usually notice it and can immediately notify the police.
if the "theft" is actually an unauthorized access to your PC, noticing is not so easy. So you can either (i) be very careful about security administration or (ii) avoid risks by keeping your media files password-protected, and possibly not physically on the PC (maybe in some cloud repository). The "digital part" of our lives gains increasing weight, and everyone of us has sensible data (personal or associated to other persons) on her/his PC: so security is an issue even if you don't have any media files, and a solution has to be found.
Next issue. You seem to think that (in my proposal) reporting a theft of media files to the police has the function of having them try to get your things back. It's not like that. The function of such a report (that can take the form of an email sent to an automatic logging system, for instance) is that of getting you off the hook if some of your files (that you bought before the time of your report) ever appear online somewhere.
(Of course if you file a report a week, someone could become suspicious...)