I concur with the statement that if there was a product whose concept was derivable by an “everyman”, that it probably would not qualify for patent protection, even if it was a billion-dollar industry. I suspect that it would be found to be “obvious”, and that its success was merely due to marketing; other people presumably would have thought of the idea before, but no one thought it was actually worth anything and so didn’t pursue it.
For instance, my grandmother claims she thought of the idea of selling fake Christmas trees with lights pre-strung decades before anyone actually started doing so. I would find it hard to believe that she’s the only one who came up with such an idea after being frustrated with putting the lights back on the tree every year when that’s the only place they’d ever be. Now, there might be some technical details about how you do such a thing and have it survive transportation, storage, etc, that my grandmother never would have realized or solved, and if such things were non-trivial to figure out, then the product as a whole might be patentable. But just the idea to sell fake Christmas trees with lights pre-strung doesn’t seem “non-obvious”.