IMHO what you are describing here is exactly one of the problems we have with the current system... creating value out of thin air. A bit of overevaluation is fine, because in the end some companies will succeed, some will fail and we're somewhat even. A classic zero-sum game. An excess of overevaluation however leads to bubbles leads to disasters.
Either way, I'd be very careful in comparing Fiat based enterprises with Bitcoin operations. Right now $413 billion are 34.7% of all USD outstanding, but given inflation it won't stay that way. The volume might increase, but it's always a run from inflation. With Bitcoin however, there's a point where it will stop. Right now there's new coins coming in, but come 50-100 years and there will be 21,000,000 BTC. End. Who knows how many USD will be out there by then? They will just keep coming and coming...
Um... bitcoin is the very definition of value out of thin air. It can't be used for ANYTHING else other than trade. It can't be used in manufacturing like gold/silver/etc, it can't be made into jewelry like diamonds... it's a straight up thin air value placeholder. The original comparison was valid, and it's perfectly OK for
market cap to be greater than available currency, because market cap represents the sum of what investors were willing to value shares (note - this is not the same as paying for shares, since not all shares were purchased at today's prices) up through today for returns in the future. Even if we suddenly rewrote the rules and made it so that mining never generated another bitcoin today, the companies that continue to provide profit to investors will trade at more than the profit they generate because investors see the value in future returns. See: P/E ratios.
The economic mechanisms at work in open markets still work with bitcoin the same as fiat, and that's OK - the main difference between fiat and bitcoin is that fiat can be printed to the extent that a single unit can be practically worthless (inflationary) while bitcoin cannot, but it can be lost (deflationary).
I wasn't talking about gold/silver/etc though, but USD. What other use has the Dollar other than trading?
It's true that it's OK for the market cap to be greater than available currency, I just don't think that it's healthy. It's of course also true that future returns are part of the value.
However I think that the question of the market cap of an enterprise / operation is inherently different in an inflationary system (ie. USD) then in a deflationary market (ie. Bitcoin). For example a sum of TWO TRILLION DOLLAR (cue Dr. Evil) is more USD than exist today, but might very well exist in 50 years and therefore be at least hypothetically transferred. A sum of 30 MILLION BITCOINS however, will always remain a fantasy. Therefore these market caps have to be viewed differently. Just my two dutch tulips.