A person could certainly treat the BTC network as a speculative opportunity, to raise the number of USD/EUR/whatever that they have. These people have no interest in BTCs other than another commodity to trade, and merely try to take advantage of gross lopsided opportunities. Since they are all competing to out-do each other, the net effect is price volatility, but also liquidity in the market.
There is a second group of people for whom bitcoins are a paradigm shift in the globalization of currencies. A digital, decentralized non-counterfeit-able marker of value is a big deal, from the perspectives of wealth transfer and ease of use (once "inside"). For these people, who are starting to think in terms of living in and earning BTC, the exchange rate only becomes an issue when people don't accept btc's for goods or services. If you know you can earn 5 btc/day (or something), then you have up to 5 btc a day to spend on whatever you need to live.