You're living under a rock.
Today is where most users, even those that have never touched a pc before are using liquid cooling parts in their computers... .
I'd say this is far from reality.
Hard core enthusiasts are only a small part of PC buyers. And even if we disregard all the rest and focus only on a enthusiast builders, it is very clear that the heyday of water cooling is behind us.
And I think one of the reasons, beside the price and almost zero gain in performance compared to better air cooling is actually availability of AIOs. Which many enthusiasts tried - and since they are generally all crap and just fail at some point, they turned many people from using any dangerous stuff in their computer.
Apart from just failing, AIOs have taken out countless motherboards, graphics cards, power supplies... And what is even more valuable, user content that was irreplacable, but with general poor backup discipline usually existed only in single copy on computers.
I also personally know people who have high end EK watercooling, but with the change of generation they just stopped bothering - when you are young a couple of years seem a long time. When you are older, even waiting to change graphics cards every second generation, CPU even less often seems like "Didn't I just replaced everything?"
Also, investing in PC parts has generally a very poor return (maybe this will change now a little with the new "Moore's Law is Dead, price of parts will not come down any more!"). But generally, selling watercooling parts after they had their use and are specific to an outdated part gets you even less return than selling those outdated CPUs, graphics cards...