Disclaimer: This is my opinion.
An article from GameStop discusses the issue of used game sales regarding the next generation consoles.
I am a software developer by trade, but I do not work in the game industry. As a gaming enthusiast, I constantly read about how developers do not gain any money on used game sales. As a developer myself, I will always support my fellow developers because I know the tediousness of coding and they've certainly earned every penny for the game they helped create.