I don't feel that downloading a copy of something you own is piracy. For example, if I want to play SMB3 NES on my PC (I own a cartridge copy. Currently. It is in my house. There's no excuses like "I owned a copy 20 years ago and I can't find it but I'm still entitled."), I will download a ROM. I do this because I am legally entitled to format shifting and no one has ever made a compelling argument why format shifting by proxy is materially different to format shifting yourself. On the other hand, I rip my own PSP games and my own DVDs, so the reason why I choose format shifting by proxy in other cases is because it's simply more convenient.
I don't care what the law says on the matter, although it's worth noting that there haven't really been any test cases (the MP3.com case did hold that it was illegal to provide format shifted-by-proxy content, but not that it was illegal to obtain), and format shifting / time shifting / fair use stuff is generally a pretty sparse field to begin with.
That being said, your question is slightly different. You aren't really asking "am I entitled to download a copy of something I own?" (I would generally agree with this--if your disc is scratched, even moreso), you're asking "am I entitled to download a copy of something I own so that I can artificially leave my physical copy unused so that I can profit more from it later?".
I can't come up with a good argument WHY opening the game, ripping the disc, and playing would be different than leaving the game closed, downloading the game, and playing, but something about it intuitively feels like you're scamming the system.