Other altcoins that ARE GPU mineable, like Ethereum and Monero and Zclassic, with the emphasis right now on Ethereum since there are more GPUs mining it than all other coins combined, are what are driving the current GPU shortage (and the one for a few months this summer) that is causing the gouge pricing.
Massive GAMER sales of GPUs this year is a bigger factor though - PC sales in general were up a lot, higher-end machines with high-end Intel and AMD Ryzen CPUs intended for gamers were up a lot more, and discrete GPU sales were up even more.
It would appear that Nvidia had it's best "Christmas sales season" in several years, AMD did as well on both the CPU AND the GPU sides, Intel probably did so too but I've not seen Intel 4Q numbers yet - and the foundries that make all the current stuff have been running at full capacity for as long as they have existed as it is.