And if you buy a watch and disassemble it and locate and purchase all the third-party parts the watchmaker manafactured it with, and put a second exactly duplicated watch together on your own, you have deprived the original watchmaker the revenue of had you purchased it from him, that was his “intellectual property” in knowing what parts to use where. Have you stolen from him? Why was he entitled to have you buy it from him?
If it was patented, then you have stolen from him. And you wouldn’t even need to take it apart and copy it, since you could just look up how to do it from public documents through the patent office.