Even the achievement of growth can throw up new barriers. Initial success often creates a 'capacity overload', which acts as a constraint on future business. The resulting ‘cascade effect' causes the problems to pile up one upon another, at best creating alternating cycles of feast and famine, but often leading to long periods of stagnation and decline.
 
Enough small businesses achieve sustained, profitable growth to demonstrate it can be done. Enough is known about economics / commercial dynamics to create a successful formula.