Preneel’s paper highlighted how apps could siphon off identities and information including location, groups, interests, “likes,” photos and videos, relationship details, religion, and even politics from people who never opted in the certain apps, but were friends of others who had.

Source: Researchers say it was easy to take people’s data from Facebook
What they did not tell you is that these claims may be fraudulent.
I just downloaded my Twitter “data” about me. It’s an 85 page long PDF file. Twitter’s own discernment of my general interests is mostly correct – things like software, Microsoft, space news, photography and so on.
The items inferred by Twitter’s ad network partners are off in space. They believe I am a young adult aged 18-25, that I am aged 45-54 and that I am over the age of 65. They believe I am C-suite executive, and that I am retired and I like golf, football, baseball and NASCAR and attend professional sporting events (all false). They believe I am a single parent who is a soccer mom with 3 young children.
The data collected and discerned is garbage data. Total garbage.
Twitter’s dossier lists over 4,000 Twitter advertisers that have placed me in their “customer lists”. Almost all are companies for whom I have zero interest in their products or services.
Social media looks like a con game to scam advertisers out of dollars.