This started in the West, then some Easterners adopted such idea as piracy = stealing.
This kind of idea is only valid in capitalism. Though valid, it is not true.
At best, making someone else's work as your own, is called lying, not stealing. Thus, applying to the other of the 10 commandments. Stealing and Lying are distinctive in the 10 commandments for a reason.
The argument could go:
Well, if you make money out of someone else's work (without their consent), that means you are stealing from them!
First, I think we can say a lot of piracy online are not for business and yet they are being treated as stealing. So, the statement that this is stealing is false.
Secondly, ideas by someone else that do not fall in today's jurisdiction of copyright protection are being used for material gain all the time. For example, food recipes, abstract ideas, ideas that failed to get patented, etc. Somehow, these cases are not usually treated as stealing. So, there is a double standard going on here. It also proves here that the Chinese notion of "不問自取就是偷" is rather shallow. Perhaps this is due to the fact that in Chinese tradition, lie, can be sometimes be good (white lies), hence lying is a grey area while stealing is always wrong, according to Chinese tradition. In Christianity, even white lies are sinful, no exception. Therefore, when something is supposed to be a lie, but the Chinese cannot quite assign a moral value to it, they assigned such to "不問自取就是偷", making it equivalent to stealing, and thus, a wrong act, not because of lying, but because it has now been unreasonably called "stealing". But I have already disproven this Chinese statement in this paragraph earlier.
Bottom line, things that can be "taken" without actually depriving the original source owner the same things that are taken, is not really being taken (or stolen), but copied. Calling something that is copied as stolen, is just a vernacular semantics. It is acceptable by many, but invalid in logical semantics. One can say, "he lied about this being his own idea", but that is as far as it can be. I have not even touch on the fact that one cannot claim oneself as the true original source of an idea.

