Because of this, I always insist on branding on every pin I create and share for a client, even in niches where on-pin text is not generally expected or necessary, like photography (wedding photography too!), styled home decor shots such as those shared by interior designers and real estate agents, and beauty tutorials.
I create a custom watermark using a free tool called Canva so that even if someone steals your pin, which they are less likely to do if it clearly shows your logo and url on it, then the interested reader can quickly find your content anyway — once they close that gross spammer site. They know who you are and what you’re about. You’ve successfully built strong brand awareness with that image, broken link or not. And they can even use Pinterest’s built-in visual search engine feature to find identical pins that DO lead to your content.
What about fighting back? Yes, you can report stolen pins to Pinterest. That is totally an option, but it may not be your best option. The industry is split on how to handle stolen pins. That is because the more you flag pins, the more of a risk you run of Pinterest flagging YOU as a thief too. This has happened to people I know, and their account was (mistakenly) suspended for anywhere between two days to a week. The anti-spam algorithm is far from perfect.