I don't know how stupid this may sound, but why do we say dollar cost averaging, DCA, instead of Satoshi cost averaging, SCA or Bitcoin cost averaging, BCA?
Why DCA, instead of BCA?
This is owing to the fact that we could associate any legal currency with cost averaging as a strategy of investment for either short or long term durations.
Kind of funny, but you should know that DCA isn't just a strategy designed for Bitcoin investment alone. You can use it for any other type/form of investment. And mind you, you are using dollar to purchase your satoshi, and not the other way round.
And again, the dollar is globally used for international trades, just like a standard unit of measurement or something, which means that the fiat currency of your country is still valued against the dollar, even for Bitcoin DCA purposes.