MadalinStroe: Oh my, the holier than thou attitude of some people. I have a news flash for you, buying second hand games is also a grey area. That's why GOG can't just sell Command and Conquer, and then send the money into the void to EA, hoping to not get sued.
If we are to get pedantic about it,
the only legal transaction is you paying money to the rights holder, or to entities approved by the rights holder. From a law point of view everything else is illegal. Grey area, in this case, is just an invention to cover things that are not technically hurting rights holders.
EDIT: Or maybe I just misunderstood how things work, in which case somebody more knowledgeable from the GOG community will correct me.
Buying from second hand is not only legal in many countries but you even have the right to resell the product, destroy it, shove it in your ass, eat it.. You can do it all you want because you did not buy a license.. You bought a product even if digital.. See the EU statement on this matter and their pronunciation against DRM that block the reselling of license/product.. That is not grey area at all.