There's no incentive to purchase something with BitCoin if the value continues to go up. Would you spend $5 on a sandwich knowing that by the end of the day if you don't spend you may have $10 instead? BitCoin is not a currency. It's a commodity or "virtual good". The speculation around BitCoin will be its undoing.
That's a flawed argument, because you can by the sandwich for $5 worth of BTCs, and then immediately buy the BTCs back with cash.
Of course, that seems excessive for the individual user, which is why your wallet service provider will do it on your behalf and assume the risk. I imagine Coinbase will do this very soon.
Assuming that in a couple of years there will be a functioning derivatives market, the wallet service provider can then offload that risk to investors.
Speculation isn't a "bad thing", it's a natural thing that is necessary for an efficient market.
Your logic is bewildering. In your scenario, you're still essentially transacting in USD and using BTC as an investment or a store of value. You're not actually spending BTC, since you expect the value to continue rising, and you buy back the BTC. Another way of looking at it is that there's no exchange of goods in BTC, since the BTC you sell doesn't transfer to a merchant, but to another investor.
Either way, this implies BTC doesn't have intrinsic worth. The OP's argument stands: deflationary forces make it even harder to create a market in bitcoin since no one wants to trade an asset that they think will appreciate in value.
I've purchased domains (NameCheap), food (Foodler), work (contractors), and countless other little things. Checking out with bitcoin is incredibly simple and easy when compared to using credit cards. I also don't need to worry about my credit card information being compromised if someone I buy from is cracked.
I'm fairly invested into bitcoin. I buy bitcoin on a regular basis and often get paid in it. I'm not too worried about the bitcoin I spent going up in value later.
I like to think of myself as a user of the currency, not necessarily an investor.
That is cool that you're paid in BTC. If you only have BTC, then it can become your primary currency, because you have no other option.
However, as long as people have access to cash in their local currency, it doesn't make commercial sense to spend BTC.
Bitcoin is a self fulfilling prophecy because of this...
I've bought stuff at least a couple of times. Most notable was when a client paid money onto a Namecheap account (for a domain name) but accidentally missed a sub-charge (and I forgot about it too). This meant that the account balance was a few pennies short of the price of a domain. If I used my credit card or Paypal not only could I end up linking my card with someone elses account but there was also a minimum of $5 charge (you could not add pennies). So I added the remaining pennies in Bitcoins and just a few seconds latter the balance had gone up and I could buy the domain name. :) I had a very good experience and it was a lot faster than even logging in with Paypal. I would also strongly recommend Namecheap to anyone. It's a very good company.
The price was a little higher than if I had paid old fashioned money, about $700 instead of $680-690. But I needed one. I guessed the price of Bitcoin would be likely to go down temporarily, which was right. It was one way of taking some profits from the increase in value
I earn money in Bitcoin, so it is a closed loop for me.
I've bought a few ASIC miners with bitcoin. I bought two BFL Jalapenos when they came out, for $150/ea, and I just preordered a Coincraft miner for abour $3k.
I've also bought two 4TB hard drives, for about $300.
(The prices are all in USD, and the price of bitcoin when I bought each thing varies.)
I bought a used Macbook Pro for ~$300 worth of bitcoins a couple of years ago. those bitcoins are worth ~$20K. My argument for why he should accept the deal was, "they will probably go up in value". I'm happy I did it.