Ever encountered an idea and you looked at it and you were like 'hey... that's mine?'... or maybe you just recognised that someone took that idea from someone else?
No big deal.
It is not that of a big deal (unless it's really bordering copyright infringement etc. - something completely illegal).
Why did they take the idea?
People who often steal ideas are taking it, all for the wrong reasons. They want the recognition you get, the money you get and all the other perks that comes along with doing what you are doing.
Is inspiring the same thing as stealing?
Now there's nothing wrong with inspiring someone. It's beyond your control and it is bound to happen if you're accomplishing great things.
I often get approached and asked for advice regarding writing, i.e. how they can become better, how they can return to writing or how they can make a success out of it. I am more than happy to help and provide them with advice on how they can do that.
However, when people blatantly steal your style of writing or topic, I give a major side-eye. There is nothing dignified or sincere about that.
They won't be as successful because their voice is not authentic. It's not theirs. They have a facade that they have to keep up and besides the writing, the facade will become like a full-time job; it's impossible to keep up.
At some point their interest will start to fade, their work may be come sloppy and ultimately, they will fail.
I view taking a persona, a style, an idea, with little sincerity, as living a facade, keeping up appearances. It's unsustainable.