and the last thing people buying stuff or transferring money with bitcoin might not need to even know its value because it is irrelevant when you buy bitcoin to buy something right away using them.
If the cost of the item changes with the market that might be the case, but most of us are paid in fiat so if we buy at $150 and then the price drops to $75 resulting in bitcoin cost of that widget we want doubling, we are paying more of our paycheck than if we waited to buy at $75.
Thus if it looks like bitcoin is in a bubble, I'm using cash because it would suck to buy the coins and then have the price plummet before it is spent.
There's no need to risk anything if you are worried the price might go down. If you are prepared to buy bitcoins to then use them to buy goods, you can basically take one of two options depending on how risk-averse you are.
Option 1: To do this, you just need a small float of bitcoins. Don't buy the coins first, but rather hold the money (temporarily) as cash at the exchange until you are ready to purchase something. Then, once you make the purchase (with your float), you can immediately re-buy the coins at the current price. The net effect is the same (fiat -> BTC -> goods), but you have risked nothing.
Option 2: If you are confident prices may rise or at least stay the same (and can handle it if you are wrong), buy the coins first and then buy what you want with them. You may wind up getting a deal in the end vs if you had bought with fiat in the first place. There is risk this way, but as I say - if you can't handle that, go with Option 1.
I have done this (option 2) several times over the past couple of months and wound up getting a slight deal each time. Bought from bitcoinstore and the price in the end by the time I bought the goods ended up being slightly cheaper than if I had made the purchase at newegg with cash in the first place.