Singaporean author John Lim wrote an article on TODAY describing the challenges he faced as a self-published author. Being a self-published author myself, I sympathise with his situation. With that said, he made the kind of mistakes that the successful self-pubbed author cannot afford to make.
I am Singapore's first Hugo and Dragon Award nominated writer. I started writing professionally in 2015. At present, I have published 17 books. 2 of them became Amazon bestsellers. Almost all of them generated income. Only 2 did not. It's not much money, to be sure, but I can say that I haven't lost the sums that Lim had.
I am an artist. With every series and every book, I seek to push the limits of my abilities. I am also a businessman. With every book I write, I think in terms of revenue and expenditures. This is how I managed to sustain my writing career for so long, without incurring thousands of dollars in losses.
Writing for profit is a business. Starting a business does not guarantee income, but at least most entrepreneurs see some sales. Authors are the exception. Having a book does not guarantee income. The publishing world is brutal, more so for self-published authors. You can spent thousands of dollars and months to create a book, only to see no return. If you want to make money from writing, you have to treat it as a business.
You have to start with why.