2. So called, "Money" does not pay dividend... does Gold pays dividend? now on the other hand, I can lend you BTC or Gold and ask you to pay me back the principle + interest on it in BTC/Gold etc so that is that... Fiat money can yield as it can be created of thin air, no actual work required (i.e. mining for Gold or BTC)
3. Any currency, company also can be replaced by something else out there but won't why? network effect, trust and liquidity matters...