Don't build software for salons; start your own salon that uses software you create, and make that your competitive advantage. Don't know how to cut hair? Then you probably don't know what software would help in that business anyway. Find a business you can do yourself, and help yourself using your technical skills.
This is also why this (very good) advice is not so easy to follow in real life. You need multiple skillsets.
This is also why this (very good) advice is not so easy to follow in real life. You need multiple skillsets.