I encourage people to get their libraries to order this. It will get the word out about prepping. I'll lose some book sales, but I'd rather get the message out than sell a few more books.
I'm not so sure about that. Perhaps short term, but I think it would have a positive sort of rebound. People who would never buy the book will read it for free...they may buy it then or not, but for sure, they'll talk about it. They may buy it for others as gifts. Certainly, they'll tell others who will be curious (even if they won't admit it) and will buy it either because Amazon is easier than the library or because they don't want to be seen checking it out.
I volunteer at our local (all-volunteer) library. People are funny. And, incidentally, in one year, we've bought multiple sets of a particular post-apocalyptic series because, when a title's hot, books disappear. Whether it's stealing or forgetfulness....people still want to read the book.
And there's always the fact that people will want to read the next book NOW...but since they already have to wait three months for the next two, they may not want to hop on the waiting list after that. (Doncha love Amazon's at-you-house-in-two-days shipping? And Kindle's even better for feeding the immediate gratification monster.)
Anyway, lots of maybes in there...but the main thing is that I believe exposure through libraries would get your books seen by people who might otherwise not hear about them.