Why would I want to buy games available on GOG anywhere else than on GOG?

PS: Never cared about FPP

GOG: The removal of the FPP is disappointing. I'm not in your shoes to know exactly what the circumstances are but I like to think that any time there's a decision between maintaining good service and increasing profit margins (for the sake of growth rather a question of survival) that good service would win everytime. At the end of the day, I prefer to shop where the service is great and prices are fair.

Partly because this wasn't really implemented with that reason but rather to placate people's anger over implementing regional pricing after having touted 'One world, One price' for several years, as well as publishing this video on what a ripoff regional pricing is: https://www.youtube.com/watch?v=nRdfYwvGTos

I think anyone with a bit of sense always knew it wasn't going to be there forever, though it has honestly lasted longer than I expected it to.

You don't have the monopoly of having been there you know?
I was there before steam was even an actual store (it was just selling Half life and its mods). I know what I'm talking about.
When steam came, PC gaming was at its peak. We got Far Cry, UT2004, doom3... Before steam managed to wash your brain to become the go to, we had some of the greatest and still unequalled games ever made for PC; I still remember UT2k being actually advertised in the general stores (they don't even do that for console releases anymore outside of specialized stores). Not to mention the first witcher was being made.

So "well on its way out before Steam even came around."? Now this is nonsense.
Thus, I take offence before such blatant misinformation.

You appear to have misunderstood. I didn't claim PC gaming was on it's way out. I'm claiming representation of it in physical stores was on it's way out, at the very least where I lived (Netherlands). Sure the 'Call of Duty' (not that one but example) big hitter style games were there but it was impossible to find 'hidden gems' so to say, especially for the obscurer less 'visually spectacular' genres. At best you had a grab box with a bunch of shovelware in it.

Meh, campaigned for a boycott at the "good news" moment of 2014, rather spearheaded that one then. And at the time they realized that many users did NOT see DRM-free as the one main driver of GOG, but BOTH that and the one-world-one-price policy, so 2.5 weeks later they had that "getting back to our roots" announcement, which included the promise of the FPP in case of regional pricing above the US price and the choice of currency. Now, however, it seems that all too few of those who still care are left around, most having been driven away since. And I don't care enough to call for a boycott anymore. That'd imply still having any realistic hope that anything good may happen on GOG, that they may still actually care about changing the industry as opposed to just being a business like any other and just doing what is best for their bottom line.
I'm still all for one-world-one-price, definitely. The issue with regions paying less is that it's unfair to other similarly poor regions that don't get such discounts and to poor people everywhere, including in wealthier regions. But I will admittedly not make much of a fuss over the fact that publishers choose to make less of a profit in order to make games more affordable at least to some people. The far bigger problem is when they change prices to increase their profits off the backs of other people, plenty of whom are definitely not wealthy anyway.
And always demanded that games that can't be on GOG according to both their original values, so both no DRM and no regional pricing, shouldn't be on GOG at all. Yes, that obviously puts me and you, and plenty of others, on opposite sides of this "battle". No news there.
Ok, what if what a game is worth to me includes it not being sold to me, or to anyone else for that matter, for more than its base price?
Oh yes. If only everyone would, and consign it to the trash heap of history along with all other failed systems tried before it, to come up with something new and better.
Oh yes. Good image for it too.
Same about losing faith, though I did want to believe there may still be some hope again after the "getting back to our roots" thing 2.5 weeks later, and got a game at "just" 50% off at that time to mark that. But any realistic reasons for that hope, and definitely any shred of faith in them, went away a few months later when they started introducing regional pricing for the first games already in the catalog too. Limited purchases since to no more than $5.99 per game, and preferably no more than $2-$2.5, and at least 70% off. Good for you that you went all out to "vote with your wallet". If only everyone would (myself included...).
Problem being that regional pricing generally means that European customers, more recently even those from countries not using the Euro, even from the poorest EU countries, even those from Serbia and Montenegro which aren't even in the EU, tend to have to pay as if $1 USD = €1 Euro. So a $1 game with a 40% discount = $0.60 if you're in the US, but that same game would be €0.60, so $0.68, in Europe.
Yeah. Most people will put up with anything, many even ending up calling it good, that's no indicator of anything. And GOG used to do what was right. Until 5 years ago. This is just another of the many steps away since then.

Same feature could be used for making instant activation of gifts for other users - as GOG Direct User 2 User - without necessity giving them a key, I think so. They could always reject it if it is still not installed/downloaded. Maybe it would be possible to make some "inventory page" in addition, where you could manage the keys you bought.
It's my little idea.

They have my total support

EU has VAT included in the price though, US is pre- sales tax. We do pay more but that's because of our own taxes and after calculating the currency exchange a publisher actually makes less off us than a US sale (since currency diff is less than the tax)

Such irony! Man, how this site changed (to worse) in the years is sad.

Not if there's a possibility to 'store' your purchases to hand them to other users later, that'll lead to third party trading.

This is true for any physical store, including first necessities like food. It was and still isn't rare to go to multiple stores to find "the" product you want. But you don't see a big monopoly (valve) go around and force everyone to make their product work only with their approval (steam keys/DRM).

Sadly digital distribution didn't fix that. If anything it made it that it's all we can have now, the PC shelves are full of those big hitters (shelves are shared about 60/30 steam/EA/others), which all require online connectivity for "activation", and shovelware that's so unappealing you have to wonder if it's not a money laundering scheme.

But hear me:
Games that are on GOG. Get steam "physical" releases. Don't you see the perversion? Don't you see the only thing holding retail back is bad practice?
Of course shelves are going to get reduced if people are screwed over like that. And then we get excuses "lol physical is over people prefer digital!". Well no shit, why should I buy a box that only contains an activation-key? Of course I won't, it's a rip-off, the content of the box has been stripped of anything that made it worth buying in the first place! Doesn't mean we don't want physical. This is a conspiracy.

What's the difference if currently you can store your keys on the piece of paper or .txt file etc.?

Maybe think for 2 seconds before insulting someone.

The insult was in your non-argument in favour of the scam that is digital distribution against the physical market that was sabotaged to make room for it.