I did a similar one. For folks who signed into our app with Facebook login, we would go get all their Likes, all their Friends, and all their Friends' Likes. There was some vague idea that we could use this for marketing.

The data volume was huge though and it quickly filled up our database, so we shut it off and threw it all away since it didn't seem to be worth the trouble.

This was in 2012... I didn't think much of it until Cambridge Analytica.