Reverse engineering, the ethics of

I propose a very simple question that has no clear answer for it covers the ethics of proprietary ownership [whereby the inventor was responsible for creation, expenses of research and development, manufacture, and marketing], national security [that is may be justifiable to perform "reverse engineering"], and just good old individual "greed". I think this goes beyond what are commonly known as "knock offs" or mere copies. If you spent hundreds of thousands on your invention and someone took it apart to discover how it works or is constructed and remarketed the item, wouldn't you be upset?