Start something from zero to profit getting to know all the steps to do so. You might not become the most technical programmer but you'll be one that knows how to deliver real value.
Sorry to be blunt, but how does knowing how to sell software make you good at writing it? What’s the end goal of the act of writing code supposed to be?
So my point is that someone being a real "full stack" developer that is capable of creating an app from conception to market, generating value to customers that are willing to pay for it. Someone that can understand all the lifecycle of a software in place of being a great "backend developer", "frontend developer", etc.