Currency[1]: Primarily a medium of exchange.

Asset[2]: Anything that has value and can be converted to cash.

For the purpose of this or any other discussion I've made this argument, the author of the comment/post clearly confuses the two above stated words or uses them interchangeably.

Currencies, in modern economics, are control by central authorities (FED/EBC/etc) which control their performance and try to adjust them. In their optimal status, when the economy goes well currencies loose value (inflation) by 1-2%. This behavior enhances money exchange and induces a spending behavior which is viewed as good for the economy. You will buy a computer today because your money will not buy the same model/computer tomorrow. When you buy something, you fight unemployment, pay taxes to the state and so on.

The computer you buy can be an asset though. The moment you buy it, starts loosing value. You won't go to the grocery store to exchange the computer for tomatoes. You will need a medium to do that, that medium is money (and that's exactly what BTC claims to be, but up until now it's not). The computer though except from an asset is also an investment. It can help you, generate value either in form of entertainment or money (programmers/designer/etc.) but it's still not money. Sure you can exchange it for something but that's not a straight-forward process as buying beers with a currency.

The next question is: Why I should own a currency? Because the local authority (a government) impose you to use it's currency to pay taxes. Currencies are never adopted, they are always enforced to populations by supreme state governments, as means of exchange. There is no other for anyone wanting to own an inflationary currency, except for that fact that you can't do anything without it. Of course in my example, I take for granted that we're talking about a relatively healthy state. Otherwise, people will prefer a foreign, more stable (less inflationary, or deflationary if possible currency. Note that less inflationary means deflationary for them anyway).

Now, BTC introduces a currency that has some characteristics. One of them is that it's finite[4]. So, deflation is chosen here by design.

Say you have 2 credit cards: 1 from BoA with USD and one issued by a third party linked to your BTC account. You enter in a grocery store and you need to pay, which one you think most people choose? The rational choice is to use the USD because it's an inflationary currency, while BTC is not.

Then, why Satoshi choose to add deflation in BTC: Because otherwise no-one would even care holding any. What kind of value an inflationary digital (non-backed) currency could ever have? None.

Bitcoin is better viewed as Gold in digital form. Say you have 10.000.000.000 USD and you wanna convert that money into some asset. Would you chose a 5 year old asset or a 5.000 old year asset to do that? The rational (obvious) choice is gold. It's 5.000 old and pretty much stable, BTC as long as we know can turn to ~ 0 tomorrow if the big players choose to opt-out or USA/CN/EU/RU decide to ban it.

Why is all this relevant for the purpose of this discussion: Because the commenter (Aqueous iirc) is talking about bitcoin as a currency and not an as an asset.

NOTE: Currency is viewed as assets at FOREX[3] but I'm sure it's not relevant for the purpose of this discussion.

[1] http://en.wikipedia.org/wiki/Currency

[2] http://en.wikipedia.org/wiki/Asset

[3] http://en.wikipedia.org/wiki/Foreign_exchange_market

[4] 20,999,999.9769 BTC. - https://en.bitcoin.it/wiki/FAQ#How_long_will_it_take_to_gene...