Like the title says what are the rules. If I miraculously got a private key to a wallet that had Bitcoin in it but was not mine originally then does that mean I now own the wallet like finders keepers and is there any legality issues with this in the usa,uk,canada,south america. Is this more of a morality should you or should you not.
How is it a miracle that you have a private key? What you say is not true; unless you are a hacker, that can happen. But the fact that you can discover a private key for Bitcoin is an impossible thing, unless you have a friend who you know is in the field of this industry.
And let's assume that what you said is true. Is there any news of something like that happening in the crypto space that returned a large amount of bitcoin because he discovered a private one that he got in a paper wallet, or a hardware wallet, or maybe in the files of a flash drive?