Compound interest.
Let’s say you need to borrow 5000 € for your first car, but you have only 700 €. First, you’ll need to find a lender who is willing to share the risk with you. Then, you form a joint stock company (Tom’s Volvo C30 2008 incorporated), where you own 7/50 of the car and the other party owns the rest. When you have some more money, you can buy some more stocks. One day, you’ll own the whole car and the lender has all of their money back.