All manufacturers (or wholesalers or retailers) that grow big enough will run into the problem of: their potential market running out of customers that can pay

All manufacturers (or wholesalers or retailers) that grow big enough will run into the problem of: their potential market running out of customers that can pay cash up front, or easily obtain credit to purchase their product. Even "cash" accounts at things like trade businesses, where the account is more about convenience and workflow (and the professional getting paid only after the work is done) than it is credit or financing, are taking on some risk of non-payment at the end of the month in order to make business flow much faster and more smoothly, than it otherwise would. It's just a matter of what industries or businesses have the capital and the will, as well as the right risk models and opportunity costs to try and implement it all "in-house" or as a subsidiary.