Here’s some sage advice from Marco Arment to app developers who are worried about being ripped off in the app store, but it can be applied more broadly than that:
Nobody else will care as much as you do. Nobody cares who was first, and nobody cares who copied who. The public won’t defend you… This feels unfair when it happens to you, but it’s just how it goes, and the entire ecosystem benefits. Every app — even yours — includes countless “standard” and “obvious” features and designs that, at one time, weren’t. Everything is a remix.
There are out-and-out rip-offs that are worth taking on—a couple of times I’ve found that some other podcast is using the art I commissioned for The Incomparable—but beyond the most obvious and egregious, it’s not worth the effort. Part of the cost of doing business on the Internet is that people—some shady, some just tough competitors—will try to take the thing you create and use it for their own ends.
It’s not fair, but that’s life. You can rage about it and waste time and energy and money on it, but in most cases it’s better to just put your energy toward something positive.