How stable is KDP to rely on as a primary source of revenue?

It isn't even just a matter of whether KDP is stable or not, it's life itself.
Case in point? There is nothing stable about 2020.

I think only you know the real answer to this if we're being honest. You can assess how risk-averse you are better than anyone and what factors will weigh in this decision for you. I can say you need to take into consideration what can affect your income outside of just Amazon.

For example: I quit my day job after I released my first book and it outearned my job earnings over 3x in one month. I was in a unique situation though--I was on the verge of burnout, I was constantly sick and even worse my one-year-old daughter was also always sick. I worked 7-4, got home at 5:30, went through the motions of caring for a toddler, and when she was in bed by about 7:30 I would clean my house, shower, and then write until about 11 or 12... back at it the next morning at 5. My husband has a great job that's extremely stable. My day job was just covering the bills I took on to pay + daycare with no room to pay down anything else... The decision was really easy.

Even then, life can still interfere. My father was diagnosed with cancer and my mother was initially diagnosed with pulmonary fibrosis. Since then they've changed her diagnosis and he's gone through the treatments and is currently cancer-free. Another pregnancy thrown in there, and I didn't release anything in 2019. Income has fallen greatly. 2020 was another blow. It's getting better now. But my point is that you just never know what life is going to throw at you.

Tldr; KDP isn't going to be your only worry. Consider different scenarios. You know best what you can handle and what consequences could be one way or another. Almost everyone I have ever talked to on this topic will always recommend you have at the minimum a nice chunk of savings to fall back on just in case. It's good advice.

Lydniz said:

You might not like the tone, but none of it is objectively bad advice.

Click to expand...

It is bad advice because a "daily Starbucks addiction" has a short-term positive impact on mood and living, while the savings you get from not buying a coffee or snack from Starbucks wouldn't move the needle on one's retirement whatsoever.

I saw an interesting post somewhere, possibly on Twitter or reddit, about a case study where someone had a low-enough income to not save anything if they spent frivolously. They asked the question, "What if I didn't pay for any of these luxuries? What if I skimped? What if I followed the advice of people in the upper crust as they look down upon 'the poors'?"

The conclusion was that this theoretical individual removed all optional luxury from their life from their 20s to retirement age, put that money into investments... and still didn't have half the amount needed for retirement. Living as a pauper doesn't move the needle. A higher income does.

Buying a house with a mega mortgage or luxury cars? Sure, don't do that. Buying a coffee and an avocado toast? It's a rounding error for the money you need to survive once you're out of the workforce.

To answer the original question, I believe the concern about KDP suddenly shutting down an account is way overblown. If you are not doing anything shady, chances are slim.

All my stuff is in Select because I don't like the admin/marketing side of publishing. Personal choice.

I quit my job two weeks into writing my first book, but we could live (more frugally) on my husband's salary, my health insurance was through him, we were on a per diem in another country at the time, and he told me to take 14 months and we'd re-evaluate. It worked out great, but he didn't quit HIS day job with the health insurance until he was over 70, and continued to work part time for another couple years, so we had a really good cushion. I couldn’t have made this choice during any of the years we had kids at home, in college, etc. Your age and circumstances are huge factors.

Other people with crappy jobs and no employer-provided health care, but no dependents, may choose to go the all-writing route because it is really no riskier than their day job, and they feel they can always pick up a part time or full time job.

And the pandemic changes things yet again. No right answers here, just an assessment of your personal situation.

ETA: Three years ago, when my husband finally fully retired, we sold the house in the extremely pricey area and moved to my sleepy hometown. No mortgage, a huge house, and almost everything is cheaper. Peace of mind. But I like small towns. Other people need to be in a city to write.