Bitcoin is an incredibly volatile currency since its inception.
Bitcoin has become extremely popular among speculators who buy bitcoin hoping the price will continue to rise, but it isn't helping to fuel bitcoin's popularity as a currency. For example, if I plan to go on vacation in two weeks and want to set aside $1,000 in spending money, if I choose to store this money in bitcoin, its buying power could climb or fall significantly by the time I leave. Most people simply don't want to deal with that level of currency risk.
Bitcoin has to achieve some level of stability before it can be adopted as a mainstream currency.