If you start a company and you break even then you're free to not grow. As long as you're happy with the money you're making and you can pay stuff, rent, insurance, equipment, services, surprises etc then you don't need to.
But if you can do it, someone else can do it, and if they are criminally inclined, sly, lucky, or are prepared to pay people less or provide a lower quality product, or they have money to burn or are backed by people with money to burn then they can take you on and, until they are caught/run out of money/lose business due to their business practices catching up with them, they can take your business. Companies which are set up with other people's money and/or which go public are going to have to answer to the people who "own" them about why they're not making more money this year than last year and the people notionally running the company will be out of a job if they can't explain this.
But if you can do it, someone else can do it, and if they are criminally inclined, sly, lucky, or are prepared to pay people less or provide a lower quality product, or they have money to burn or are backed by people with money to burn then they can take you on and, until they are caught/run out of money/lose business due to their business practices catching up with them, they can take your business. Companies which are set up with other people's money and/or which go public are going to have to answer to the people who "own" them about why they're not making more money this year than last year and the people notionally running the company will be out of a job if they can't explain this.