Is there really such a thing as stealing someone else's idea?

Tweet

I came across this "funny" quote, which expressed that his ideas are being copied or something like that. Made me think if it's even really possible. For me, it could be that someone also has the same idea as another's. I remember when I was in high school and I was still into writing poems. There's this line I included in a poem I made, which after some time I read somewhere in a school journal. I was tempted to think that someone might have stolen my thoughts, but how was that even possible? I didn't even submitted that poem anywhere? Nor did I share it to more than a few people closest to me (including my older sister). And, there were many other similar situations after that. But, of course, it's kinda different now in this generation since there's social media. Ideas are easily shared around the globe in a matter of seconds. Either you'll be "plagiarized" or your idea will be shared by many in their own words. But, then, there are still lots in my mind that I haven't put into writing, then I'll read them somewhere in the Net. Only proves that there are people out there with similar minds as mine. So, there are times I browse the Net and find my thoughts said exactly the same way I thought of it by another person who's totally a complete stranger. Some are by people who I am acquainted to. Nevertheless, I believe that to be too concerned about "copyright" is just owning something that isn't really yours solely. We may have thought or wrote about an idea first but it doesn't mean it's all ours. Or it's an original from us. Just so happened that there are people who chose writing as their profession and they get paid for it. They claim the right to an idea, thought or creation but truth is, nobody truly owns the original. It's just a matter of who expresses it first. But, truth is, many share the same thoughts, idea, opinion... Agree?