> By fully backing each coin with a set of stable and liquid assets (described later) and by working with a competitive group of exchanges and other liquidity providers, users can have confidence that they will be able to sell any Libra coin at or close to the value of the reserve at any time. [0]
They'll fund expenses from the return of the investments.
> How will the reserve be invested? Users of Libra do not receive a return from the reserve. The reserve will be invested in low-risk assets that will yield interest over time. The revenue from this interest will first go to support the operating expenses of the association — to fund investments in the growth and development of the ecosystem, grants to nonprofit and multilateral organizations, engineering research, etc. [0]
Brokerages do this as well and earn most of their money this way (people keep cash in brokerage account and brokerage invests and earns interest).
> 57% of Schwab’s revenues are from net interest. The firm could literally give away every other service; discount the mutual fund fees to zero, do away with commissions, etc etc, and they would still be profitable. [1]
[0] https://libra.org/en-US/about-currency-reserve/#the_reserve
[1] https://www.kalzumeus.com/2019/6/26/how-brokerages-make-mone...