I do not really trust Facebook and what its doing. I deleted my Facebook long ago because i know my data was never safe with them. There was not much alternative out there but then I finally found one that at least made an effort to protect your data. Vid uses zero knowledge encryption and on top of that, lets you monetize your auto generated memory should you choose to publicize it.
Dollar $, Euro €, GBP, Yen are back by nothing (gold standard canceled by President Nixon 1971). So, Facebook "Libra" is backed by Dollar $, Euro €, GBP, Yen. In conclusion Facebook Libra = backed by nothing
cheer