Things will mysteriously start to work again, flawlessly, once you give up trying to fix them.
Windows will always find a way to piss you off, and it will twist the knife at the same time.
Failure of one OS suddenly makes you think your alternative (working!) OS is utterly perfect in every single way - even though in real life it is not.
Having a second system is incredibly useful and comforting.
Being lazy about backing data up results in fear and panic, so it is better to just keep things backed up constantly, no matter how safe you think you are.