The sales may devaluate games, but before online shops that was done by the second hand market and limited releases.
Often a year later the same game would be released by a different distributor often for only a fraction of the original price.
Of course it had a different box. Collectors would try to get the original version for the full price or on second hand market.
These days it does not make a difference where you buy your game from or when or at what price. So of course I go for the cheapest option.

Sales have nothing to do with this, as game prices are still lowering over time nowadays. Here are a few examples:

https://www.gogdb.org/product/1371948460
https://www.gogdb.org/product/1389682947
https://www.gogdb.org/product/2109390794

They may have been correct, but if this post is meant to encourage GOG to stop having deep discounts and so many sales, personally I'm not interested (at least the deep discounts).

2012 was over a decade ago, and strategies and the make-up of companies change. It's possible GOG might not even be here if they didn't try to remain competitive (which I guess a few people might have okay with, preferring GOG to die the hero...). Frankly I'm okay with with the deep discounts because I don't have lots of money to spend.

If people want to support a dev, they can make the choice to buy at full-price or buy multiple keys and give them away. Or one could buy on Zoom-Platform when possible; they rarely have sales or discounts like GOG back in the day.
(Fireflower Games might have a similar policy; not sure about itch.io but I assume that's on a per-dev basis.)

And as a result I rarely buy games there. I have bought some exclusives that i actually want to play and / or preserve, but otherwise I stay away. On the other hand, I throw hundreds at GOG every month, for games that I will probably never play.

Some people think that discounts equate to lost profits. Maybe that's true for modern and / or really popular games (which is why Nintendo barely has sales), but when it comes to older and / or less popular titles, a discount equates to actually gaining a sale.

As I mentioned in my previous posts, I do buy games at full price, I even pre-order some of them. However I also buy thousands of games on sale too. If they weren't on sale, I would have never bought them (like I don't on ZP). Those are not lost profits due to discounts. Those are gained profits due to discounts. You can either hope that someone may buy 1 copy at full price, or you can have 20 people buy it for 1/3 of the price.

ZP did have a little sale awhile ago and I bought up everything then. I wouldn't have if there was no sale. So what's better? No sale, or sale at a discount? It depends on the demand of the product and every store should try to evaluate this to the best of their ability.

I don't know a single person, who doesn't have random games in their Steam library, that they have never played and probably never will play. So why did they buy them? Heavy discounts. It's psychological! GOG seem to have learned that. So once again, discounts are not losses. Discounts are big wins.

Thanks for supporting GOG but please be careful about spending this much (though I'm guessing you're pretty financially secure).

I should control my spending better actually, because I waste all my disposable income on it, meaning that I save nothing for a rainy day lol.

Heh, yeah sounds like something to consider. ;)

On rainy days I play games so it's a win-win.