Not everything is in the exponential growth model. Most small businesses in your town for example. Margins might afford an upper middle class lifestyle for the owner and that is a good enough business model for this company to last decades, even pass down through the family.

On the micro level, I agree. On the macro level, I don't know how viable those businesses will be when the wider economy is no longer growing exponentially (and frankly that may well be the least of all concerns).