It’s not about Libra. It’s about legitimacy and what legitimacy infers. It could, for example, help soften India’s stance on cryptocurrencies, and with population of 1.3 billion people, what effect would legalising cryptocurrency in India have on the market?
It’s unknown, but Facebook’s entry into cryptocurrency adds a variable that needs to be priced in. It’s often not the news itself, but the implications of the news that has the most effect.