This was just a number that somebody pulled out of their ass. How they arrived at that number is anybodys guess.

Its all based on how many people actually USE IT. If people dont USE IT, and there are few goods/services to buy, and obtaining BTC is difficult - then even if the coins are $25k each, Bitcoin isnt really valuable.

Sure, having a $25k coin would be nice but its unlikely unless Bitcoin is able to really change the world. The ideas embodied in Bitcoin - decentralized, peer-to-peer based consensus mechanism, can be applied to a variety of fields which are only now begining to come to light. If those applications pan out, the seeds of Bitcoin could result in a totally open internet, decentralized corporations and governments - exponential efficiency gains. Its use as a currency/payment method is only the beginning.

Bitcoins Fair Value is directly related to how many people are actively using it, not the price.