Why do better MC cartridges cost a fortune?

There is the pretense that there is something (audio quality) which there is not. The analogy is with the listeners/onlookers who sheepishly follow the flock.
Of course there are recordings that are not on cd and only on lp. I still have my turntable for those, but I find I rarely if ever use it. The reality is that streaming services now offer such a wide selection that no private music collection could ever compete. I have a busy job, but if I had time I would digitize all my lp's and just get over with it.

These are for the rich only!

The rich audio buffs are usually not scientists or engineers, and lack basic technology understanding, to "fine tune" the turntable/arm/ cartridge setup. Their systems rarely have optimal sound quality. They "throw money away" and believe high cost = best.

They go for "snob appeal" to impress other rich friends.

Proper arm/cartridge setup with expensive $1K to $3K, (but not ridiculous) cartridges is all you need for SOTA sound!

There is no rational justification for spending $10K to $15K on a cartridge IMO.

YES I have heard the big buck cartridges FYI.

The problem with old cartridges is that their suspensions may have dried out.

Rich people are as diverse as the rest. What is often true is that my 10 dollars is their one dollar or less.
Also, not all audiophiles who have great systems are exactly rich. They have been improving their set-ups for many years and eventually might have systems that sound incredible and would cost over $100k if everything was bought new now.
Bill, I heard of Air Tight cartridges. Balanced warm sounding?

To repeat myself - cartridges don't last long if you play them a lot, they are disposable elements in the system. If you buy $10k cartridges in a number of years you will have spent $100k. How does it sound to a reasonable ear, $100k for cartridges?