BAs don't need to create/run a business to be successful. However, the fundamentals in finance, logistics, etc. allow starting to deliver value soon.
One of the beauties of Business Analysis job is that you never know what your next project is going to be. Will it be a product for financial reporting or evaluating a company's share price? A tool to manage privacy in public information? A functionality to assort products for a huge retail store chain? An airplanes / hotels booking engine? You name it. A Business Analyst should have a basic understanding of different domains (for example, Finance, Documentation, Retail, Hotels / Airlines - as mentioned above). We suggest reading articles from Harvard Business Review, a wonderful magazine that is on the table of C-Suite of the top companies: those people share their experience in the HBR articles. By the way, many of them are available for free once you sign up.