I never understood this. :-/
What's to understand? Some people are assholes. They like to horde things rather than do the right thing and make information free.
If I had something like that, assuming I didn't pay a small fortune for it, I'd make a disk image of it and let everyone that wanted one have one and to freely distribute the copies they have. Even if I did pay a small fortune, I'd still set up a donation thing and as soon as I got back what I paid for it, I'd release the disk images for free from that point forward.
I just have always hated the idea of keeping things from people just to say I have the only copy. That's just bullshit and being a jerk.