It takes two to barter.
> treating it effectively like a foreign currency
They really aren't. They accept bitcoins in exchange for goods/services, just like we see in any barter system.
Calling bitcoins "foreign currency" is just a desperate attempt to hide the obvious consequences of it's volatility, which eliminates it's role as money, not only as a store of value but also as unit of account.
Each and every single random guy on the internet who wants to buy stuff with money cares about money, and the properties that allow something to work as money.
Specifically, properties like being stable in its value within the market, and reliable both as a means of deferred payments and meet debts.
Bitcoin, or any cryptocurrency, is nothing of the sort. Far from it.
For some random guys on the internet. yes. Some other guys are using it without waiting for it to be everything the previous system had. (deferred payments etc.).
No, it's not. It’s too volatile to be an efficient store of value or a useful unit of account for general purposes; it's got some use as a competitive medium of exchange for certain circumstances (but again not really with the generality of any major fiat currency.)
It's commodity that seems to (retrospectively, at least, and there is some reason to expect this to continue for the near future) have good investment performance if you are in a position to wait out down periods, which makes it nice as a component of an investment portfolio.
It's good at things that aren't the purpose of money, but mostly not good for things that are the purposes of money, except for a narrow subset of one of three major purposes of money.
Bitcoin is obviously not money, and among the many reasons the fact that it does not serve as a store of value nor a means to defer payments, which is a single requirement that comprised the very definition of money, is just one of them.
Just because a random guy barters bitcoins for goods/services, that by no means implies that bitcoin is anything close to money.
There is a very specific definition of what money is, and bitcoin's volatility alone rules it completely out.