“..not their demography” is bad conclusion, IMHO. Demography can help one identify the commonality in the circumstances that you’re talking about. To me, “Market is not just about demography”. I’m afraid there are several poor/dangerous examples cited to get to your conclusion. In fact, I don’t even see how they add up to your conclusion. For instance, the notion that elderly people do eat pizza doesn’t make them count at least initially for a fatty-pizza startup. Let’s pause for a moment and try thinking of successful start-ups that targeted the whole world of people to begin with. I can’t name one such company. It doesn’t help one to focus and build a right product, when your target market is wide. So typically, one asks and recommends to narrow down the target segment. And demography is just one of those elements. Hope I made myself clear. Cheers!