I've also been listening to this advice for a long time: "Build your catalog, don't put money into advertising, and watch your sales grow organically!" And yeah, my books are not building naturally to bigger amounts of money. If I put out a new book, sometimes people buy it, but more often than not my books get ignored. There's too much competition and once a new release sinks in the ranks it's virtually invisible to readers.
So now I'm trying to learn advertising. Even just experimenting with a few months, I'm already getting better results. Not great, but better than when I did nothing.
But a book advance from writing (and money in most types of creative work) is not the same as a salary. This writer keeps talking about things like, "Why am I getting pay cut?" You didn't get a pay cut, your third book deal was just less money than the first. It wasn't a guaranteed salary.
If you want a reliable salary, find another job.
I didn't have a mentor to take me under their wing or a fancy MFA program. (Took one creative writing class which had zero business advice.) But I did see someone say online once: no one owes you anything for your book. It's not "If you build it, they will come" and "Everyone deserves to tell their story!" You can put your blood, sweat, and tears into your work, but that's meaningless to the rest of the world. No one has to buy your book, or give it a five-star review, or hand you awards.
Even if you are this week's hot new release and #1 on a bestseller list, that won't last. Book 1 selling well does not mean book 2 will also succeed.
And I'm tired of how many people brag about being (fiction) writers but their real income seems to be from "author mentoring" or "how to succeed in Amazon ads online course" or some other service. This writer clearly falls into that category. The "woe is me" article is an ad for you to pay to learn from her mistakes.