If you run your own show, then sales are the only thing you can do to feed the kids, at least in the long run. The money that comes from sales is yours to do with as you wish.
Yet you cannot get a university degree in selling. They do not exist.
Nor can you get a degree in direct marketing or online marketing. These niche forms of marketing take up three lessons in an entire degree course on brand marketing. But these are the easiest, cheapest, most powerful ways to find people who want what you sell.
You can borrow money, but you need to give that back. That hurts, and you cannot borrow for long without sales to repay the first loan. So, sales are utterly crucial. And sales come from finding enough people who want what you sell. (That is the part called marketing.)
Yet, after meeting with thousands of people who own their own firms, I know just one thing: They all focus on what the firm does, rather than on selling what the firm does. Maybe that is why so few of us survive?