The truth is that the amount of money you can make from self-publishing will depend largely on you and the effort you put into it. Since you don't have a publisher to handle your marketing, distribution, and other aspects of getting your book out there, you have to take all that responsibility on yourself. That means if you don't invest a significant amount of time and energy, you won't make very much.
Some indie authors manage to make a full-time living just from the income generated from their books. Others manage to scrape together some supplemental income. It really varies from person to person, and not all authors have the same level of success.
In order to make more money from your books, it's important that you understand how self-publishing works. You should be familiar with the different distribution platforms, such as Amazon, Apple and Kobo, as well as understand how pricing and promotion works. Being knowledgeable will help you create a more successful publishing plan.
It's also important that you build an audience who will be interested in your books. That means actively marketing to potential readers, such as doing blog tours, taking part in online conversations and participating in book fairs and other events.
It's also important to keep exploring and trying new methods or strategies. Self-publishing is a rapidly evolving industry, so it pays to stay up to date with the trends and changes.
Ultimately, the amount of money you make from self-publishing will depend on you and your dedication to delivering quality work, marketing strategically and continuously exploring new opportunities.