In the last 6 months, I've never held onto a bitcoin for more than about 30 minutes. Strictly use them for their utility as a currency.
But because retailers will only hold onto them for probably seconds, using BTC as a transfer medium won't significantly affect the price: average selling and buying will be the same.
The only way BTC can go up is if more people hold on to more of them (reducing the available money supply), which when they are rising happens more, causing a bubble.
As far as the cost of using them, while it is non-zero, some of us just want to do our part in establishing a currency and surrounding ecosystem that is free from gov't, corporate, and other meddling. Thus we accept the small hit in price.