Libracoin is a stable coin, which means it shouldn't go up and down. The purpose of this coin is tracking your payment activity and sell this statistics to companies who wants to sell some products based on this statictics.
In my opinion, Libra Coin will be the main currency on Facebook platform. About who wants to buy, I think many investors are lining up to buy because Libra coin used to transact on Facebook. I think, Facebook will develop seriously the marketplace on its platform
From what I read, facebook really do created a facebook currency that will only be used in the facebook network, According to what I read its really not a cryptocurrency, yes it uses blockchain technology, but it just like a fiat that and its price is not volatile and it's not even in any marketplace.
Ref:
https://www.coindesk.com/libra-isnt-a-cryptocurrency-its-a-glimpse-of-a-new-asset-class