The chance of GPS going down is very low. Close to nil. The chance of it going down at the exact second one might need it is even lower.

Failure of some kind of the GPS unit, including battery failure, is of course possible. I suspect anyone relying on anything with batteries will have spares. But it could be dropped, or sat on and broken like a lot of things.

But it is also not real hard to break a compass, or to lose it. It is also not unheard of for local oddities such as deposits of magnetic materials to throw a compass off by a substantial amount.

I once had a similar discussion with a guy who absolutely was convinced that only a mil-spec compass with tritium backlight was worthy. I kept trying to get him to tell me why I could not use my flashlight to look at the compass at night, or why I would want to. Eventually he said it was because when one is on patrol at night one does not want the enemy to see the flashlight. I also got a line about how one could still use a compass that had a tritium backlight, even if one had no flashlight. I did get some kind of a response about walking in the desert at night so one could walk when it is cooler, which made more sense than the patrol idea to me. I never got much of an answer when I asked how he was planning to walk in the dark without a flashlight. NV maybe. Sometimes it is not real productive to try and get people past their preconceived notions.

I am not going out on patrol any time soon. When I go out in the woods it is recreational in nature. I would never go anywhere any distance from civilization without a map and a compass. These days I would not go without a GPS either. I think of them as a backup to each other, even though I am not the world's most adroit user of GPS. That is something I should probably practice more.