Say you are from a third world country. Your family back home needs money, but a bunch of red tape and fees in the traditional finance system (sending money to a third world country often raises KYC/AML questions and wire transfer fees are high) make it difficult and expensive. Moreover, in some countries with unstable currencies such as Lebanon and Argentina, the banks have to offer government mandated exchange rates that are wildly off the effective rates; there have even been cases where FX deposits were forcibly converted to the local currencies at these unrealistic rates. Rather than go through all this, you can just send BTC and sidestep all the issues.