Don't want to bring a wall of gibberish text with my bad grammar here.

Just: why this game wasn't on weekly/seasonal sale since 2017, according to ITAD and my own wishlist (it's most old game in it right here, by the date it was added here I means, and for a long time)?

Is there any real reason?

the same applies to "Terminator: Resistance", what I've been waiting for.

Why wait three years or more for a discount? That's plenty of time to save enough money to pay the difference.

in my case this is because i'm simply not willing to pay so much money for this game and also it's not really an AAA Title.
furthermore the game was discounted several times on Steam but never on GOG since i had it on my wishlist.

Personally i refuse to buy games at $60. At $20 i would relunctantly buy.

Most of my collection i bought at 80% or higher off, or used console games on disc for $5 a pop.

Depends far more if you want to be economically efficient, if you want to play the game now, or if you want the most games for your buck.

To cut the long story short: Chaos Overlords in my wishlist indeed, but I doesn't put it on the same level with Metal Gear Solid 1/2, Contra/Castlevania, Soldier of Fortune, XIII, Mortal Kombat 4, Blade Runner, Warcraft I/II, Warlords I/II/III, Diablo, Street of Rage 4 etc. - these are games that I've purchased instantly when they were released here.

There are priorities and so I'm waiting for a pricedrop on this game to buy it.

First I agreed with you... but then I saw the default price of the game is 5.09€.

I mean, come on. There's not much room for a discount.

The price for "Chaos Overlords" is 5,09€ which is ok, but that was not my post. ;-)
I stated about "Terminator: Resistance" and it actually would cost 39,99€.