Dangers from extending water fasting? fatty liver?

While I've read about all of the amazing benefits from fasting, but I also read these accounts of people doing extending Water Fasts and then being diagnosed with fatty liver- and these people were healthy before water fasting.

I've also read people who say their health has been worse ever since fasting, and that it can cause SIBO, organ damage, etc.

Maybe we're wrong about extended fasting? Maybe it is very dangerous and we're making a huge mistake?