alt + J
Well when I happens I get upset, of course, but at the same time I remember that there’s not much I can do. It gets tiring to ask people to stop stealing your photos and you will never find everyone who does it. My advice - unless they’re profiting from it (ex. using it for an album cover or advertisement), just let it go. You can try things like posting your photos in a lower resolution or adding a watermark. I haven’t done either of those because I think it’s important for people to have the best experience when viewing photos.
Yes, stealing photos is terrible but it’s not the end of the world. It’s more important to enjoy sharing your photos than to get revenge on those who steal them.