Having had several ideas stolen from me without so much as a thank you when I was a younger writer I have been very careful about sending books, plays and ‘ideas’ out to anyone. And when I read what happened to other people’s ideas my experiences are mild.
There are many people who suggest registering a new book, and time stamping your submissions with a lawyer so if a work appears that is very similar you can at least tell if it might have been stolen or not. Of course there are those that are just coincidence and these days every major film sets aside a fund to defend itself against being sued as so many people want to make a film the ideas are often similar. Nowadays if you don’t have an agent even film companies won’t look at your work.
The problem with this behaviour is one of money, publishers having put money into making the career of one writer don’t want to take on another. The ‘idea’ that there are only a few good thriller writers or other genre writers is of course, absurd. Genre books are very simple to write and the digital revolution is giving many more the chance to get known.
But in the main thieves don’t respect the idea, they just want the money.