FFVII was only 3 discs, which topped out would be in the neighborhood of 2.1GB.
FFVIII was 4 discs, so around 2.8GB.
I don't remember IX, but 3 discs again I think.
So, no, 4GB each is a vast exaggeration. Besides, 32GB for $100? I paid $75 for 512MB back at the PSP launch for a MS Pro Duo --...