One of the most important things in business is to think scalable. If you want to start a business and dimension it only for the first 100 customers, than something is wrong with your plans and the business will most likely fail. We all see success stories from people that started a business without anticipating its grow, but this usually happens with businesses that offer something very innovative and in very few cases (I could not find any official statistics regarding this, but I am sure that less than the success rate in these conditions is less than 0.01%).