Community hype/peer pressure made Kraken Club the absurd price that it is right now. I haven't used mine in months, and really only use it on BST or Naegling RNG (hence the months). Kraken club isn't really "worth" a billion gil, it just got hyped up a lot. I probably wouldn't even be able to sell it for a 900M in today's market. But its still an ultra fun weapon to use.
Eiryl's right, though. All of those factor into why Krakens aren't moving on Asura. RMT can't mass buy them and move them to another server (without losing the account from Asura), and people won't migrate here just for a Kraken only to not be able to return home. The result is tons of clubs people don't have anything to do with.
There's a couple of other things that killed off KC too. Weapon Skill walls; Normally you pair KC with Naegling and Savage spam all the things, people now want each DD to kind of have their own strong unique WS, so group damage doesn't dip too low. Prime weapons are strong enough, SC very well, and don't wall another person unless it's the same job/weapon. Primes are another indirect reason why KC fell off. An example would be DRG would normally use KC and spam Savage, but Gae Buide 4/5 is just amazing. I've heard from many people (myself included) who enjoy using Prime instead of Savage/Kclub, and if you need to Savage, just sub WAR. You unlock Judgment. You pair Prime weapons with Hoxne Ampulla and the right STP build, and you gain TP at an absurd rate. I can't really think of many jobs after DRG that benefit a lot from Kraken Club (BST mostly, RNG, BRD kinda?)
I'm surprised it hasn't tanked in price (nobody wants to be the guy to drop it to 50% asking price)