I've heard, facebook's cryptocurrency, Libra, should become a stablecoin.... but how can they ensure that it stays stable, if it's traded on a market and the value of it depends on demand and supply? If it gets rare, it will become expensive, no matter if it's backed by fiat currencies (this fact could help the coin not to fall below a certain value)- but who guarants that it won't get 10 times the price of it's underlying currencies? This cryptocurrency still has an independent price that is dictated by the market, if listed on an excahnge then- and not by facebook! ... it only can get stable, if the number of coins is not fixed- but this is a vital point in all cryptocurrencies!!