The standard option would be to simply grab all the installers and pop them onto an external HDD, but those things will need replacing every decade or so and I don't want to need backups of my backups.
Frankly, I never understand these suggestions that downloading the installers to a hard drive is a worse option than to burn the installers one by one to optical media (e.g. DVD-R). I see only benefits to downloading them to a hard drive.
Having the installers on a hard drive makes it much easier to manage your library, and find the game you are looking for from your local library. Easier to detect that you don't have obsolete duplicates of the same game.
Keeping the installers up to date is also far easier when you can simply replace the old files with new downloaded ones on your hard drive, instead of re-burning all the optical discs that have received even a tiny update. The other option, I guess, would be that you never update your installers, but I find that option silly. Often the games do get very important updates, and also for older games, they get updates so that they work also with the latest Windows OSes (e.g. Windows 10).
Also, if you want to check whether all your GOG installers are still ok (not corrupted), you can easily check them all in one swoop with tools like dvdsig, rhash or even gogrepo's verify command. How do you do the same for hundreds or thousands of optical discs? Pop them into your DVD drive one by one and check the files?
The argument that "you have to replace the storage HDD every ten years or so" is odd for a couple of reasons:
- Burned optical discs need to be replaced even more often. As I've told before, 1-2 years ago I started a project to move all my old stuff from old optical (burned) discs to my hard drives, just so that I could throw those optical discs to trashbin and manage the files in them more easily, e.g. to get rid of obsole files I don't need anymore (because I e.g. have a newer version already). Turns out that quite many of those optical discs have indeed become unreadable over the years (ie. errors when trying to copy the files from them). Off the top of my head I'd say that well over 10% of them had become corrupted.
- It is quite natural to replace your hard drives every now and then anyway. Do you still actively use all your decade old hard drives? I think the more common way is that as hard drives become bigger and faster, you move all your old stuff from the old hard drives to the one bigger hard drive. For instance, I remember when my biggest hard drives were maybe 300GB but I am not really using those anymore. I have already copied all the stuff I want from them to bigger, e.g. 3 terabyte, hard drive(s).
So if you e.g. now would keep your GOG installers on a 1 TB hard drive, maybe in 10 years you have already moved them several times to bigger hard drives, like to a 10TB, then to a 100TB, then 1000TB, then 100000000000000001 TB...
Last but not least, depending on optical discs means that you will have to have an optical drive also far in the future. In my eyes optical drives (for computer use) are already obsolete and are on their way out. Many PCs (laptops) don't even have an internal optical drive anymore, USB memory sticks and USB hard drives work much better for any local removable storage use, etc. Are you sure you will even have a working optical drive capable reading your old DVD-R discs in the future? Those drives are pretty delicate things, the read/write head in them is quite heavy (compared to e.g. HDD heads) hence break up pretty easily, the laser might become non-aligned or dirty, the optical drive tray mechanism (open/close) tend to become broken over time etc.
The only benefit for using hundreds/thousands of optical discs (instead of a couple of hard drives) I've heard is the "having all eggs in one basket" argument, ie. if that hard drive becomes broken, you lose all your games at once, while with optical discs you lose only those which become broken.
I find that argument a bit silly too. Naturally you don't keep only one copy of your stuff, you keep backup hard drives too (you can do this manually like I do, or those RAID thingamalings that many do). Also as long as GOG is around, their online servers is also one place where you have your backups. The question about keeping several local (or cloud) backups of your GOG installers becomes really relevant only if and when it seems GOG is on its way out permanently, like DotEmu is doing now (yes, I have my DotEmu game installers now on three different hard drives).