Here is a good article about how hard it is to get filthy fiat for bitcoins in Canada, the place with the Bitcoin ATM machine.
conceivably there's a cutoff point where no-one at all can afford to mine the coins anymore?
As @CHR1S says though, the hashing difficulty varies every 20 or so days (can't remember the exact number) so that the time to process a block of transactions is always 10 minutes regardless of the networks total hashing power. If people started switching off their rigs, or fewer people mined, the difficulty would drop and so potentially cause mining to be profitable again. This is incredibly unlikely to happen though. If it did happen, it would inevitably make the news and would lead to more idiots buying mining rigs to try and get money for nothing, so we'd just be back where we started.
For the record, the bitcoin network currently uses somewhere between 1.5 and 2 Large Hadron Colliders worth of power. That's a lot of people doing a lot of useless calculations for very little internet money.
Edit: Bitcoiners also say that it's the mining network is powerful supercomputer in the world. It can only compute SHA-1 hashes though, so it's completely useless in every possible way.
The crash is coming!
This finance expert thinks Bitcoin will fall 99 percent by June « Washington Post
There is a downward trend predicted over the next 24/48 hours, some even say a crash.
I'm only learning to read the markets so posting it here more as a record of my prediction than anything. Lets see how my guess goes! (and no I have no cash invested in BTC)
A crash is inevitable since the chinese gov have banned the currency, and before the ban the chinese exchange was trading in over 48% of the total trade volume worldwide.
So let me get this all straight..
There's this one secretive guy, who's come up with this crypto-currency idea that everyone is buying into, and recently it has been announced that not only could this be the go to solution for the pending 'debt-backed currency' doom, but it could also handle the exchange of legal documents (Stateless company puts legal documents into Bitcoin blockchain - Imperica - digital arts and culture magazine) and other such things to keep them present, correct and provable. Nah, that doesn't sound like the plot to a bad world domination movie at all!!
Seriously though, I mean, it's interesting as a proof of concept, and I wish all those (including a good friend of mine who won't shut up about it .. you can't actually have a conversation without it being mentioned that I should start a mining rig in one of my barns) good luck and hope that people are wise enough to (as with shares and such) sell at the right time to make their money, but a decentralised monetary system is surely only decentralised in the fact that it's a peer to peer network, so can't be closed down, but you still need a centralised system at present to be able to exchange these into sensible (read spendable) currency ..
There's just something that doesn't quite sit right with it all for me .. but I would love to be proven wrong ..
This is interesting.
927 People Own Half Of The Bitcoins - Business Insider
Saw this article today as well: Bitcoin Is Broken :: Hacking, Distributed
I'm really not suprised there's a flaw like this in proof of concept software though.