I'm not going to stare and drool at my keyboard all day. I have plenty of nice thick sets that cost me a fraction of what the big names would that look great. Some might not have perfect mold marks beneath, but I'm also not ever looking at the bottoms of the caps either. Unless I want some fun novelty like metal caps on one of my K65s, or something to better match the themes of the case than whatever came on it, I usually leave caps alone. I would also give an exception for the paint on the cheap backlit caps wearing off, but even that has never happened to me. My most-used K70s are shined like a mirror but the legends are still perfect. I have a few sets of PBT double shots I got cheap on Aliexpress for them, but I'm still conflicted on 1) Whether or not I care enough to bother swapping them and 2) Whether or not I'll put up with their texture, since I actually love shined caps.
It's more than that...The more expensive keycaps are more expensive for a reason. Generally the quality is better and you can tell by touch and sound that they feel better.
How are you going to tell any caps apart from each other at all by feel other than profile, material, and texture? How do we quantify what is and is not high quality? Do I need to buy a $150 set of hunks of plastic to compare against the $40 set of hunks of plastic that cosmetically look no worse from above? What justifies such a disparity in price other than exclusivity/limited production? My cheap shined ABS caps don't feel any better or worse to me than my thick double shot PBT caps. There's a difference in sound, sure, but even that's a subjective preference, just like people obsessing over matte finishes or vice versa, and I can't imagine how that could have anything to do with a $150 set vs a $40 set if they're made of the same material and are of the same thickness.
Have you actually tried some of the more expensive different sets or are you just speculating? You sound exactly like someone whose actually never owned and used any of the more premium keycaps sets..
But lets break it down..
Do they look cosmetically different from above..yes..generally the quality of the Doubleshot and dye sub printing is better on some of the higher quality keycaps. That's not to say GMK or others are perfect...they're not. But the cleaner lines, the alignment and overall finish tends to be better. It is noticeable when you see them and more noticeable side by side.
Feel..
Completely subjective..but the better caps tend to feel a bit more solid. This isn't necessarily thickness..there are some cheap thick PBT that feel...cheap and they often suffer from other issues. But regardless, if your preference is for "thinner" caps or ones that have a "cheaper" feel that's fine. The more expensive caps have a different feel - and for those that prefer that feel, they'll need to spend more. That "feel" tends to come from what seems like a more expensive process....There are some custom keycaps that I think feel meh but they're expensive because of the colorway and layout support - we don't see keycaps made from some of those makers any longer or not as much anyways...
And as you tend to do this..just because YOU don't feel the difference doesn't mean other people do not. Great. You're lucky. You prefer how cheap keycaps feel = you're lucky. Sometimes ignorance is bliss. For me, the feel is noticeably different and while I would much rather pay almost nothing for keycaps, my experience is they don't feel as good.
Lets also not forget that many of the premium sets have support for other layouts and other options and of course a look/design that is unique. I will say, the pricing for GMK has gotten out of control. On the plus side, there are so many GMK sets out there now it is super easy to find something. On the downside, it is more of a business now than a community project.
So here's how the price comes about.
Higher Quality Control
Higher Quality manufacturing process.
Lower Quantity = less scale = greater unit price
Higher Margins - I'd imagine there are greater margins there with companies building a premium produce rather than razor thin margins of a much more mass produced product.
I mean, I get it..you don't like spending a ton of money on stuff...We've had this same discussion about the quality of keyboards where you equate most of it to the switch which is probably why you have your choice of keyboard and keycaps...The fact that you can't tell the difference is just you. I'm sure you can't tell the difference in the quality of wine either right? For any enthusiasts hobby there are going to be a good number of people who can see the difference in quality...and some that are just posers..and some that don't see the difference. Lets face it, the best place to be is where you end up spending the least amount of money and get exactly the same enjoyment, that's just not reality for some.