That's how a few hundred thousand people taking a "personality quiz" gets turned into millions of user-data.
And the term personality quiz is used loosely, an example of a "personality quiz" can be "Which Game of Thrones character are you? This isn't rigorous psycometrics.
Social networks were extrapolated from friend data. Cambridge analytica was able to use social connections to profile people and who they know.
That was the extent of it.
This isn't "propaganda put out by intelligence agencies", and there are not "37 million idiots" who "took a 'personality quiz' allowing the 'app' to access their information".
But he already explained that to you quite clearly, something you should have already known if you were following the real news, and you still don't get it.
But since you choose to subscribe to the conspiracy theory that this is just all deep state propaganda, and everyone whose privacy was compromised was an idiot who asked for it by doing something foolish and deserves what they got, then there's no use in discussing it with you.
Because you're their ideal target and they've already successfully targeted you and influenced your mind, even though you didn't take a personality quiz yourself.
So what happened here? Facebook users who took a 'personality quiz' allowed the 'app' to access their information.
It is extremely depressing that 87 million people are idiots.
There are intrusive apps all over facebook and this is being released with a narrative that supports 'election interference'.