Facebook buys offline data gathered by marketers or gathered from other sources
apnews.com
apnews.com
Doesn't mean we can't change how things are done. It'll be an interesting public discourse now that some light is being shined on these practices.
Why would you want to or need to? (I'm asking seriously.)
Purchase data from multiple sources with the intention of connecting more dots. It helps them get around most of the data is anonymous.