Why might a person want to start a business?

To get a lot of money.

Actually though you should never start a business to make a lot of money. That is a great method to failure. Businesses that succeed are there for the purpose of filling a need they see. That need is worth money and they can charge for that service or good that is needed. If you start a business for the purpose of filling a need, you are far more likely to succeed.

Microsoft saw a need for a cheap operating system. They made one and became wealthy. Not because they chased money, but because they saw a huge need and could fill that need. Fill a need and you will win every time.