I have over 100 topo maps, of mostly CA, and know how to use them.
That said I was an early GPS user and own some nice Garmin units, Magellan too.
Using a GPS absolutely reduces your ability to use maps because you use them so much less.
I have vacationed on a motorbike crossing the continent 3 times and never even touched a paper map.
If the lights ever do go out, everyone under 40 will be screwed.
The % of people over 40 who could use a map was pretty small. Roadmaps, maybe. Anything more complicated than that was strictly hobbyist - orienteering, or military. Back bearings, triangulation, allowing for local declination when converting a compass bearing to a map bearing etc. Fun stuff, but it’s a perishable skill, too.
I don’t want to think about how dependent aircraft or ships might be. Do they still carry charts and maps of their route? Contingency planning for complete loss of GPS? Yeesh.
I have a couple of boxes with a bunch of topo maps. Every time I see them as I’m moving something to try to find something else I think I should just toss them to make more room. I just don’t have the heart to though. Although I’m 98% sure that I’ll never use them again.