If you download the installers you are literally making a copy. Since you still have access to the files on the Gog server. Making copies for personal use is allowed but selling the copies is not because of copyright laws. There is no digital store that facilitates reselling where you can transfer the license of one game to someone else.
That doesn’t give you the right to resell, rent or even giveaway that. Which is what the first sale doctrine allows you to. Not to mention that GoG is one store, which proves it’s not a law since others can do it differently.
Yes, you can.
GOG allows you to download the installers for use offline.
If you download the installers you are literally making a copy. Since you still have access to the files on the Gog server. Making copies for personal use is allowed but selling the copies is not because of copyright laws. There is no digital store that facilitates reselling where you can transfer the license of one game to someone else.
That doesn’t give you the right to resell, rent or even giveaway that. Which is what the first sale doctrine allows you to. Not to mention that GoG is one store, which proves it’s not a law since others can do it differently.