You guys clearly all have vested interest in Bitcoin, this is the hornets nest after all. I am heavily invested in Bitcoin, but I see it for what it is.
It is a Pyramid, the price is determined by miners and the mining manufacturers who produce the hardware at a set cost. When you purchase that hardware, that is your "buy-in" price. From the time you purchase that hardware, you are unlikely to see a ROI, unless you are lucky. The Manufacturers mine with your hardware for a few months until ROI is no longer possible and blame it on delays, the Manufacturers then begin producing the next wave of machines with 3-10x the amount of hashing power. For the 90% of people who get their machines and start running into ROI problems, they begin hoarding all the coins they have mined, as if they were to sell them they would be selling at a loss. They hoard them in hopes the price will go up, as the entire network of consumers who does this occurs, there is less Bitcoins on the exchanges for sale. Less demand --> higher prices. All it takes is a wift of good news at these points and you will see the 20-90x increase hills that have happened time and time again. This process usually occurs in 4-8 month periods.
While this is true, you are forgetting the other angle.
As hardware is very scarce, the demand for good hardware will be high, both from savvy miners that calculate precisely the ROI of a machine and from filthy casuals that click forum/google ads regarding BFL miners with hope to get into the game. This causes the price to be higher than perfect ROI, thus leading to your scenario, but not from the offer's side but from the demand side. Higher price demands more mining and raises difficulty, too high difficulty demands a higher price.
However, once new Bitcoins cost X dollars to make and because miners will raise the floor and acquire the cheaper ones (remember they WANT the actual bitcoins as collectibles, not necessarily to ROI on hardware) the system will mostly grow in size and adoption, the new price of Bitcoin is set in stone slowly by having transactions made on this new price.
Without a technological or infrastructure flaw, or maybe a better replacement with simpler and better design (like Dogecoin) , Bitcoin is still and will be valuable and will have no reason to drop in price until it engulfs sufficient value to replace some currencies. Even if we end up using only Bitcoin, it's relative value will still increase as coins are lost, destroyed or saved for later. Consider for a bit just how cheap Bitcoin will make our financial system. No more banks, safes, coins, bills, stock markets, people to operate them, places to store them, buildings, communications, infrastructure, risk funds. How many resources we can release for other constructive purposes in our society, besides handling our collective effort rewards.
Not a bubble, in the same way as trains, automobiles, radios, televisions and internet connections are not.