[sahila]

Because if you/they knew that, then they'd be buying more bitcoin.

On a much smaller scale, your dollar goes up by 5% every year but you still use it everyday because all your monies are in dollars. If all your monies are in btc, you'd have to sell to buy things.

[cg5280]

If you suppose that BTC would be a widely adopted currency, you wouldn't "sell" it, you would simply exchange it for the good or service. But in this case if BTC is deflationary you would still hesitate to spend it. USD is inflationary, so there is hypothetically a small pressure to use it.