I guess Bitcoin is turning out to be the Esperanto of money

Somehow I don't think that you mean that as a compliment.

> are those things denominated in fiat currency or in bitcoin

By your logic if I exchange dollars for euros to spend on a vacation somewhere that means the dollar has failed ?

Bitcoin is volatile. That's the main issue. You can't say that about the dollar or euro.

Now imagine you get paid in bitcoin, save every month for a holiday or a high value purchase. When the time comes to make the purchase you find out that your savings are worth less than 10%. How does it feel using bitcoin?

I tried to use bitcoin(as a merchant) but due its volatility it makes no sense to use it(as merchant or buyer).

Its volatile because it is relatively new and not backed by a government. Market forces are having their way.It will stabilize

At this point, it's a feature to have things denominated in $. I'm likely going to buy a Purism laptop with bitcoin, but of course denominated in $. I spent a couple hundred on BTC years ago, which has generated a nice return. This will be my first purchase, and I'll have plenty of BTC left over. Holding a deflationary currency while the world operates on an inflationary one is fine by me.

Both