First you need to learn computer languages like PHP, PYTHON, NODEJS, HTML, CSS, JAVASCRIPT, JAVA, SWIFT, KOTLIN, C, C++ etc. Depending on what are you trying to do. For example, If you want to build websites, you need to learn languages like PHP, PYTHON, NODEJS for backend and HTML, CSS and JAVASCRIPT for frontend. For Mobile apps, you need to learn REACT NATIVE which is JAVASCRIPT or FLUTTER (DART) or SWIFT or JAVA or KOTLIN. I think you know what I mean. Plus you can't master these languages over night so you need to invest some of your time if you can self study otherwise you need to invest some time and money to go to school.
Now, once you learn these languages, you need to create Apps or websites which is going to need lots of your time because it is not just about creating and selling it to other people, you also need to provide services like fixing bugs and keeping your product up to date to catchup with changing technology. For example, if you have created an App for iOS 16 and when iOS 17 comes along, you might need to upgrade your App depending on the compatibility with Operating System. If you have created websites, You might need to upgrade for example when PHP 5 gets deprecated.
So the bottom line is, it is not like any other products, you buy or create them, sell them and you don't want to talk about it anymore. No wonder, lots of programmer look weird, grumpy and depressed.
Another way to make money from your skill is to get a job or jobs. Because of it's broad nature, most of the people end up getting job. Plus it is not that easy to get a job, you need to be really good at what you are doing.
So, if you are thinking about Elon Musk, in this context. Think again, How much sacrifice you have to make? How much time you have to invest? to get to his position. If you are family type, forget about. When you take this path, you are going to be lonely most of the time. You will become different person than that who you once used to be.