For “rare” games like some of my oldies from the 80s and 90s (one or two that weren’t even on the abandonware sites last I checked) I have ISOs I ripped and store on my NAS. Same with stuff bought form smaller/sketchier stores (I am sure it is backed up millions of times over, but think Romero’s Sigil).
For gog or steam or whatever games? I just don’t bother. The French Monk Incident more or less taught me there is zero chance of maintaining archives of GoG games. Their servers are “fine” at the best of times (let alone when the site is “dead”) and they don’t publicize when an installer is updated or not.
So if gog or steam or whatever goes offline and I still really want to play… Darklands? Piracy.
Way back at the start of GoG (I want to say year one), CDP did the “joke” of suddenly taking down the entire site except for a text page saying they are shutting down. I forget if they said that people would have 24 hours to back up their games or if they said we were up shit creek, it doesn’t matter.
They then basically said “Ha ha, april fools! But you see, that is why you should buy all your games from us because we are DRM free and you own them”. Which… rightfully angered a LOT of people.
So GoG did a video where a “french monk” (which is really weird since they are Polish but…) apologized and gave away a discount code or something. And in The Witcher 2, an NPC was added who alluded to all this and I think gave away a free copy of The Witcher 1 if you beat him at dice poker or whatever?
Short term? It led to a lot of us actually trying to back up our games. And realizing that was not feasible because GoG would almost never post changelogs or let us know which installers had updated versions and ain’t nobody got time to manually scrape every download page. Long term? You can generally tell who was a “GoG OG” in that we look at ANY “And we are the best site ever because we have no DRM and preserve everything” bit of PR from GoG/CDP because it is painfully obvious this is just advertisement for them.