Re: Did Satoshi steal other people's ideas for Bitcoin and one reason why he left?
I have had many silent thoughts on this matter and I contemplated the outcome of this experiment, if Satoshi decided to reveal his true identity. How many people would actually take him to court for intellectual copyright infringement? Companies like PayPal revolutionized person-to-person payments online and they might even find a reason to sue him. 
You can't copyright an idea (at least, in the U.S.). The key word here is "expression". You can copyright the expression of an idea, but you can't copyright the idea itself. Satoshi used the ideas of several other people to develop Bitcoin, but he did not copy the expressions of those ideas (the words that they wrote), so there is no basis for copyright infringement.
Here's an example of the difference: The Winklevoss twins did not sue Mark Zuckerberg because he turned their idea for a website into Facebook. They sued him because he worked with them on their idea and then used the results of that work (the intellectual property) to start Facebook.
Similarly, you can't patent an concept, but you can patent an implementation of the concept. Nobody can patent the concept of a decentralized peer-to-peer electronic cash system, but Satoshi can certainly patent Bitcoin, which is an implementation of that concept.
Anyway, although I have researched this subject extensively, I'm not an expert, so my post may contain some inaccuracies.