How did people get their first million when they started with almost no money?

The people in these videos mostly got their first money by starting small and funding the business themselves. Andy Frisella's company began with $12,000 and a store about the size of a flag, and he and his partners kept money coming in through bartending and other side hustles while the business grew slowly. Sarah Blakeley started Spanx with $5,000 she had saved from selling fax machines door to door for seven years, and she never took outside investors. Jim Cook, who created Samuel Adams, stripped his startup to the bare minimum: he contracted production at an existing brewery instead of building one, used bars as his office, and went without an office for a year. One billionaire in another video said he started his first business with $300, and Michael Weistrach said he had $15 in his bank account when he started his company and was $1 million in debt.