Why do better MC cartridges cost a fortune?

Now that's the price of a record !
Yeah, electrical power is a never ending struggle. Here, in addition to a very dirty current, voltage fluctuates from 115 to 128. PS Audio Premier does stabilize it and cleans it pretty good, but if it is too bad it spends a lot of energy on itself and the dynamics gets compromized. Still incomparably better than without it. Power cords from the wall to the regenerator make a difference, by the way.
Unpgrading your amps/speakers set-up would be a huge undertaking, that would probably take the entire system to the ultimate level.

Herzan looks serious. Swiss things. How do they compare to Vibroplanes?

Active isolation like the Herzan (or similar from many others including KSI who make Vibraplanes) offers 99% isolation in all six dimensions. Passive such as Vibraplane maxes out at 95% or so and more effective in vertical than horizontal. Also latter requires a compressor for air supply. Cost is 30-40% of active however and certainly will give great results, as will other passive approaches such as Minus-K, do note however that the latter need to be loaded as specified for best results whereas active platforms perform under any load. So, many ways to slay the isolation dragon 🐉 

Yeah, this could be interesting dilemma for some. If you have $10k to upgrade your analog front end and your table arm and phono seem just fine but cartridge and isolation could be better, what do you do? Do you spend it all on Herzan active, supercartridge or do 3/7 split and get Minus-K platform and another cartridge? And how can you know in advance? I suppose, you can return the platforms if bought from authorized dealers or directly, though. But not cartridges. The answer to this question is, I think, you have to develop 'audiophile instinct'. It will not always be right but in most cases it will.

They charge and we gladly pay? And you have to retip or replace it soon enough. Most of them come from Japan. They sure know how to do business, don’t they?

No, the manufacturer is the poor one.
The real winners are those in the following distributor chain and when we go down to the core... your "enemy" is the audiophile next to you who wants to spend more :-)
Supported by deaf reviewers ....