Why are you so convinced that everyone would immediately want to use Libra? Do you think the Euro is such a mess? If that’s really the case, wouldn’t some people using an alternate currency be a step forward?

If Libra is going to be more economically than a typical bank, that will take many years and give plenty of time to react in case of problems. Also, it should first be up to the people for themselves to decide what means of payment they are using. The government should only intervene when the market fails.