i had a similar issue whe i posted my car pictures on reddit using flickr links and then someone messagd me on FB letting me know that a popular e46 group on instagram posed a pic of my car but didnt credit the owner or photographer. i commented on the image saying "hey thats my car how about a mention of my use rname" but nothing.. then DMd them on instagram and got no response but they continued posting more pictures of other cars.... basically they make money posting other peoples cars usually with permission and since they had so many followers they leverage that for advertising with other companies etc...
since 3 days went by with no reply i just filed a copyright claim with instagram and the post was removed along with the 5000+ likes it hadin a few hours. then they messaged me back saying hey why did you do that.
some people are just really entitled and have no clue how the world works.