If they remained a small business by choice of the owners, then the owners might be called "micropreneurs".
Some people by choice don't expand their businesses, usually not having more than five employees. Micropreneurs are business people willing to acknowledge the danger of beginning and dealing with the sort of business that remaining small, gives them a chance to do the sort of work they need to do, and offers them an adjusted way of life. Numerous business people remain little by decision.