I understood what you meant, however I don't think you understand what I mean. Having people set their own prices(used games) have not killed the industry and still won't. Remember, physical games weren't that long ago. You have to look at this from a stand point of physical first. When you purchase a physical game, you are then able to sell it to someone else. It's unfortunate that a company can't profit from this, but at the point of owning the disc it's not up to them to decide what they want from your purchase.
Now, lets say for example all digital purchases became physical all of a sudden. What I'm proposing is that Microsoft(and/or the company that put out the product) can take a percentage of your sell when you sell said product. So, they still had the initial sale from when you bought it, you get paid a set amount, and they also had a profit from when you sold it to another person. Tell me, how is this not a better system than GameStop's or a full on refund? Clearly we can't create a situation where everyone gets what they want, but we could theoretically tweak how things currently work. You eliminate the shady middleman of Gamestop(having them buy low and sell high) and put this type of selling system into the users hands as long as they agree with the percentage policies set by companies.
I'm not just talking about 'offering cheaper' because clearly costs have risen exponentially in the past decade. I'm talking about someone who bought a 60 dollar game, selling it to another person for 55 ish dollars, and the company/companies still making a good percentage profit from that. Like a disc, you would not get the additional DLC(like many companies are injecting in games nowadays anyway to combat used sales) so there's also a possible additional profit from that as well. For some reason you have this belief that a ton of people will undercut others to such a high degree that they don't get money from their sale to another person. However, if the user knows that a percentage of their sale would be taken by said companies, why would they price as low as possible? Why would anyone sell a game for 0.05 cents to get rid of it and earn barely anything at all? The only way I see that happening is if the game has barely a dollar value to begin with.
I'd rather hear your extended thoughts on what I propose and maybe of a way to improve it, rather than just accepting the way things currently are and telling me 'you don't understand' yet again.