"Make sure you try one. I think you'll change your mind." - Dave, I got my first fatbike about twelve years ago, and the Surly Pugsley will always have a place in my heart, no matter how many fatbikes today are much, much better.
2013 was really the watershed year for fatbikes, with every major manufacturer finally releasing a fat model. 2016 was the year that fatbike sales peaked, and have been declining ever since, largely attributed to the popularity of plus-sized bikes (approx. 3 inch tires). There will always be a place for fatbikes, but it's not the only answer. Anecdotally, nearly all of the people I knew that bought fatbikes have sold them on since then and only a few still ride them regularly.
Bikes come and go, and sometimes we get to build something that's really a hit. Given that we have a hard time keeping the Compass in stock, it seems to be doing pretty well. We keep building more and more of them, and they keep getting bought up, sometimes before the shipment even makes it stateside.
Regarding mid-drives in general, "if the motor stops so does the chain and they can't be pedaled." I'm not sure which drive system you're referring to, but that sounds awful and nobody should buy that bike. You should be able to pedal independently of the motor. (This is one of the reasons I don't like direct-drive hub motors for ebikes.)
I don't want GFmucci to feel left out... Our battery isn't cheap; we sell the best batteries we can get our hands on. It is, however, competitive. We sell the 48V 11.6AH Compass battery for $800 shipped in the lower 48. Pedego sells their 48V 11.0AH battery for $929, so we're $129 less expensive, and we offer a much longer warranty. Can you find cheaper batteries? Absolutely. Are they truly equivalent? Maybe not; be sure to get all the details when buying a battery, especially from less well-known sources.
Cheers,
David