perry_blueberry said:
some people seem unable to make a single rational decision during their lifetime
They are probably rational, just using a skewed or inaccurate understanding of facts or relationships or causality.
Also, yes, for a single human being, they may end up buying a steak anyway and then be late on their electricity bill, because steak is freakin' delicious and the monkey brain wants it.
My point is that, overall, the concept of substitute products is much more important to marketing, than the idea that there's either a sale, or there isn't, in a vacuum. Your product is always a substitute for some other use for that money (even if that substitute is “saving it for a rainy day.”) The customer has to believe that you will deliver more value than the substitutes, whether that's emotionally or rationally or (usually) a combination of both. And for that to happen, you need to both reach the customer with your message, and have that message be the right one. And the main reason “actually making a good game” is important to marketing, is that messages about bad games will reach people through channels you don't control yourself, so you're not in 100% control of your marketing, no matter how much time and money you spend on it!