Having been in a few failing businesses I can tell you that marketing and sales are _the_ core reason tech (maybe also non-tech) businesses fail. Fundamentally you can do without code, but you can't do without sales.
I have a lot of respect for sales people and people who can market themselves. One of my favorite videos about this is by a bodybuilder/powerlifter Stan Efferding [1] - he is some sort of marketing savant, with a product that I think is kind of silly, but he can market the hell out of it.