Well he is partially right. It should read, "If you make a good game AND you PROVE IT TO THEM, people will buy it." Meaning you can't just make a good game and expect people to know it is a good game. You make a good game and then through marketing, hype, and reviews you prove it to them. It doesn't mean you'll have a knockout but, games that have good word of mouth tend to sell well at least over long periods of time so you'll have that.
Only exceptions to this rule is of course games that are quite "niche" in nature. Only one that seems to have broken that mold is Valkyria Chronicles, but I doubt our sales numbers, and doubt other things on it that would cause it to break that mold haha. But ya get the point.
A lot of times it just seems devs sacrifice one for the other which shows a lack of faith on both fronts.