Just a question for VoD, Even Microsoft doesn't care about cracked Windows versions and lets people to use them.
Latest statement about this: "cracked windows users will get windows 10 upgrade for free": http://www.windowscentral.com/you-can-upgrade-windows-10-free-even-if-youre-using-pirated-version-windows

Why do you care about people's selling Msdn keys?

Yes, it's unethical, wrong, maybe illegal but even Microsoft doesn't care, why do you?

Also people may just crack and use it for free (with viruses of course), And this may cause bitcoin theft...