Winter is coming, and so is the weather that comes with it: high winds, heavy ran, snow, and ice, all of which can cause the power grid to go down during the night. Blackouts are an inconvenience for everyone, but they're particularly worrisome for people who rely on electricity to run their medical equipment.
CPAP users fall into this category. Without a steady source of power or a ready backup option (like a battery pack), your CPAP machine will stop running when the power goes out. You'll be getting by without treatment for your apnea until the grid comes back online.
Similarly, if you're traveling and you don't have a reliable source of compatible electric current for your machine, you won't be able to comply with your therapy. (For example, if you're in a country with different outlets, or if you're camping or residing in a temporary shelter.)
No power to your CPAP machine means you'll be living with untreated apnea and snoring until electricity becomes available again. Anyone who's lived with obstructive sleep apnea knows what that means.