A picture of you with the subject "I know what you were looking at when I took this picture of you" is pretty good blackmail--I think there's an active campaign doing this even.

This would've been blackmail 20 years ago.... nowadays it's just "of course you know, I shared my OF likes publicly", will not even raise an eyebrow; or perhaps I'm living in too bohemian society circles

I received a phishing email from this campaign or a similar one several months ago. The email opened with my name and contained a Google Maps photo of a house where I'd lived 8 years before. The author claimed to have hacked my laptop and captured videos of me doing embarrassing things. They would release the videos unless I paid them $1000 in Bitcoin. I searched and it's an extremely common scam, but I did panic for a few minutes.

Excellent blackmail against teenagers. Pointless against me as an adult.