@delphidb96: I agree. Thanks for your post
And don't forget the last two points:
1. You may loose that 5% of "book-stealers" - but you save lots and lots of money with reduced overall costs (e.g. printing, etc)
2. Noone speaks of abolishing copyright - and no, contrary to what publishers tell you, not using DRM does NOT mean you withdraw your copyrights.