can anyone explain this term please? ... so who are we afraid of?<<<<
As others have pointed out, it's TEOTWAWKI, not TEOTWANKO.
As for the second question, nobody's afraid of anything. As you have noticed, "survival" books are somewhat popular right now. In fact, I have one that's doing modestly well. It's just basic information that I've previously made available for free elsewhere, but it keeps making modest sales, and I'm going to be doing another one that's more optimized for Kindle. The one I currently have sells a dozen copies a month for 99 cents. From that modest success, I see where a good book that goes into more detail about one sub-topic would probably sell a few dozen copies a month at $2.99 or more. So yes, there's money to be made.
But if you're interested in writing such books, you do need to understand the customers of this sort of book. And, in fact, they're not afraid of anything. Nobody's afraid of anything.
Your target audience generally views the world's entire population as being in one of two categories. The largest segment of the population is sometimes referred to as "DGI's", which stands for "Don't Get It". The DGI's aren't afraid of anything, because they are blissfully unaware of any threat. So there's no fear in the DGI world, and they're certainly not going to buy any books that cater to fears, because they don't have any.
The rest of the world (the ones that buy the books) "gets it", and understands that there is a threat of some kind. There are actually many underlying threats, and among those who "get it", there will be different opinions as to what the underlying threat is. In fact, if one person is focusing on one threat, and someone else is focusing on another threat, then they might even consider one another to be DGI's.
But in general, whatever the underlying threat is, what binds your target demographic together is the belief that on the heals of the underlying threat taking place, there will soon be a general breakdown in society, rioting, pillaging, looting, etc.
But in general, those who "get it" aren't afraid of anything, either. They're not afraid of the rioting, pillaging, looting, etc. They have a little secret. They're actually kind of looking forward to it. As soon as the rioting, pillaging, and looting begins, there won't be any taxes to pay. There won't be any electric bill. There won't be any mortgage. Of course, there won't be any food, but you can always grow food, and you can deal with the folks rioting down the street, as long as you don't have to waste your time worrying about the mortgage payment.
So the long and short of this is that nobody is afraid of anything. So books that cater to fear won't sell anything.
I'm personally in a very small minority. I'm generally in the DGI camp myself, not because I think that those underlying events are impossible or even improbable. Eventually, Yellowstone is going to blow, or the meteorite is going to hit, or someone will nuke us, or something bad will happen. Where I differ from most of those who "get it" is that I don't share the belief that there will be immediate rioting, pillaging, and looting. I'm sure there will be some, but probably not nearly as much as predicted by those who "get it".
I probably wouldn't be able to write a very good book on dealing with rioting, pillaging, and looting, since I'm a DGI when it comes to those subjects. And the kind of people who read survival books can spot a DGI from a mile away, so I'm not going to bother trying. Where I can write a good book is when it comes to some rational discussion of the underlying threats, backed up by actual facts. My books don't address the rioting and looting, one way or another. If there's rioting and looting, my books will still be useful for their scientific content about the underlying causes. And if there is no rioting or looting, they'll be equally useful. In fact, they'll be seen as more credible than the books about rioting and looting.
In fact, I have this nagging suspicion that even after Yellowstone blows, I'll still need to pay taxes and pay the mortgage. So that's the main thing I'm afraid of. But I'm in a pretty small minority.
But I have never paid on any mortgage, they pay me on mortgages I hold. What am I supposed to be afraid of? Taxes? I was thinking a war with OZ. But then, what about Greece? There's rioting and looting there, and over reduction in social spending. What if there were no social programs in the US because the US dollar is worthless? That just might cause some rioting in the US, you think? I do not think anyone but a few pimple-faced kids are actually wanting a TEOTWAWKI. This is like teen boys thinking war is fun... until they actually are in one. Adults would rather not live through TWOTWAWKI. But there is that news video of the US soldier exclaiming (in the middle of a battle), "I love this s---!" There is no accounting for teen insanity.
Not sure what "pronk" is all about, though knew TEOTWAWKI. Next time you're in a bar and see the following behind the bar - IITYWIMWYBMAD_ and you ask about i, you deserve to pay up (It stands for "If I tell you what it means would you buy me a drink"). You'd be surprised how many ask and fall for it!