I think this is more complicated: the problem is not going out and talking to a bunch of strangers (which I would do if necessary, and I do claim that my tolerance of rejection is sufficiently high).

The problem rather is (this is something that a friend, who works as a business consultant, explained to me): to make a successful sale, you need a salesperson "who thinks like the customer". Lots of programmers simply think very differently from how the typical programmers, and thus are bad salespersons concerning these customers.

He really said that I have an insanely good intuition for what kind of software product would insanely help some specific industry, but also honestly told me that I (and honestly also he) would likely not be capable of selling such a product (if it existed) to a customer in this industry, simply because I think too differently from the decision makers in this industry.