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I for one am unclear why that's a distortion of your argument. People don't stop needing things just because holding on to money longer can mean you'll get more value for it tomorrow.
We arent talking about money in general. You can buy stuff online with creditcard, bankwire, paypal, etc... and decentralized, anonymous currency - bitcoin (good idea only as long as its stable and reliable payment option).
Obvious trend is: many who have bitcoins that become a lot more valuable with each passing week (compared to real money like $, EUR, whatever), do see it as an investment and are more and more reactant to buy stuff with bitcoin.
People are only reluctant to buy using bitcoins if they think the price is going to keep going up like it has been. If I bout 10 dollars of bitcoins, and now they are worth 20 dollars, then I have no problem spending half of them to buy something, it is like getting it for free and I still have 10 dollars worth of bitcoins.