Because the majority who buy it don't use it as currency. They are speculating with something virtual and like to believe it is more valuable than gold or paper. Thus since it is all speculation and the price is way overvalued, the price must come down. I mean at least the Germans could wallpaper their house when their money became useless.
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Wait, what?
That doesn't make ANY sense at all.
1) Your first statement, the foundation of your argument, applies to volume but not to population
Rephrase your statement and it is correct.
The majority of PEOPLE who buy it DO use it as currency. The majority of BITCOINS are not used as currency, rather, they are saved (or as the occupy wall st. bears like to say, "hoarded.") Just like with any other currency. There are a FEW rich people who have lots of bitcoins, but most of them DO use coins for standard purchases, they just have so many that they would never need to spend anywhere near all of them. There are a LOT of not-so-rich people who have a few bitcoins, and have an equal basic need for goods and services and use bitcoins for them. They are your thousands upon thousands of nerds who have some saved for appreciation, and some used for various things - webhosting, computer parts, precious metals, online purchases, etc. Like Elwar buying dog food with bitcoins - is he "using it as a currency" because he bought dog food with it, or is he an "evil speculator" because he also has a cold wallet full of coins?
Your statement that most "People" with bitcoins don't use it as currency, only as speculation, is not only wrong, it is unprovable since it lacks a method for validation -
what percent of total held coins must be spent on a regular basis in order to be considered a "person who uses bitcoin as a currency?" Does a person who spends 50% of his coins regularly qualify as a "spender" but somone who spends 24% qualify as an evil speculator? At least start by making a claim that can be disproved.
2) When the statement is rephrased to refer to volume rather than population, i.e. the only way it could be correct, it applies equally to fiat money.
The vast majority of PEOPLE with viat money (99.9999%) use it as a currency.
However, the vast majority of the TOTAL VOLUME of fiat money is used for speculation (many quadrillions in the futures market, which is many times more than the remaining quantity of money on the entire earth.) Fiat money has only novelty value as a wallpaper so that is a moot point. Even if bitcoin was worth 1 cent, I could instantly send it to someone in Bangkok, anonymously and for a very low fee. I can't do that with a piece of paper after it hyperinflates, falls out of favor, and is not accepted anywhere except in my authoritarian country.
(Try passing a Cypriot-marked euro in Germany or an Argentinian peso in any other country, heck, try even leaving the countries with those bills in your wallet without getting arrested. Capital controls are a bitch.)