Bitcoin wouldn't replace the credit card because no merchant in their right mind would forgo payments in USD for BTC with BITC's price volatility. Are you guys serious? BTC behaves more like a commodity or store of value than a currency. Everyone hoards it.
True under current conditions. Speculators buy it because it is believed that it will be useful as a currency in the future. As more bitcoin is used as currency rather than commodity, then the price will stabilize, or be more predictable, IMHO.
Speculators buy it because they believe the value will go up...big difference from believing it'll be used in the future.
There's some famous quotes from major institutions and investors from the real estate crash in 2008 and the tech crash of the late 90s about how they knew what they were buying was overvalued, but they bought it anyway because they thought they would be smart enough to sell before the bubble burst.