The way I see it is that there are a number of ingredients involved in successfully doing a startup: Marketing, sales, finance, people, luck, ambition, domain knowledge, etc. You can be weak in one area but then you'll have to compensate in other areas to make it up.
I know a very successful founder of a tech company (yearly turnover 8 figures), and he has no idea how to hack. But he does have acute people skills, and he's brilliant at sales. He was also lucky that he got into a domain that had a lot of possibility.
I also know a guy that's a brilliant programmer, but his projects never go anywhere. He doesn't know how to sell his product, and he's afraid of giving up control. The inevitable result is that noone has ever heard of him or his company.