Bitcoin will eventually stabilize in value. Lots of currencies fluctuate.
Hence forex. Y'all know what forex is, right? Yes, you can speculate in the currency market, but currency is not the same thing as stock and suchlike.
SpookyCash sites accept payment in Euros, Pounds, and Yen as well and, just like everyone else does this, US affiliates get paid out in whatever that was worth in dollars at the time of payment.
Here is the Dictionary.com definition of
currency, for those of y'all who are still approaching Bitcoin like it is stock.