Your data on FB is worth precisely one thing to them: the ability to target you with ads on FB. When you don't use FB, it's useless to them.
Add to that the risk of them not providing good enough security regarding access to the data (such as with the Cambridge Analytica case), and giving them access to so much of your data becomes an additional problem to consider, since you have no control over that data sharing whatsoever.
Facebook Audience Network is a display ad network like Adwords.
It's deployed widely across the web and mobile apps.