David Marcus, the head of Facebook's cryptocurrency Libra twitted,
Many want to pit Libra vs. Bitcoin. In my mind these two are not in the same category. BTC is a decorrelated (investment) asset. Libra is designed to be a stable medium-of-exchange. I have been, and remain a fan of BTC, but for very different purposes.
The former president of Paypal stressed that Libra is a better digital cash and payment system, while bitcoin is a long-term investment vehicle.
https://www.ccn.com/crypto/facebook-cryptocurrency-chief-libra-no-threat-to-bitcoin/2019/06/20/I think the people says Libra is threat to bitcoin are the hired shill from facebook from doing this they can attract the people attention on their coin and then claiming that they are better medium of exchange to convince them to invest on it.