The difference with physical is that you own the physical medium the license is stored on and are permitted to sell the physical medium with the license. With digital downloads you are not allowed to sell a drive with the files. Since you are technically making a copy.
The worth of a gog game secondhand is 0 though. Theres nothing to be made there.
People do sell accounts though.
Isn’t there a clause in baldur’s gate 3 terms that lets you transfer the game license once to a friend or something along those lines?
Not sure how that works but it’d be cool if we can have that apply for all of them (digitally) maybe like 3 times over the lifetime of the licensed game.
Only thing I could find was section 5 which relates to eldritch law. Worth a read!