They identified a niche, bootstrapped their company, solved a real pain point for their customers, and spread through word of mouth from their satisfied customers to become the dominant player in their space.
* They didn't invest in redundant systems * They had problems at scale * They had high running costs * They took health and safety risks with their employees
Slightly related movie suggestions, based on their interruptive theme: "Field of Dreams", "Moneyball", "The Wolfs of Wall Street"
http://www.imdb.com/title/tt1251757/
The bell idea was great.