They're not used everywhere, most stuff desktop or servers are now based on SSD or equivalent.
Your use case of people running desktop with 100TB is niche, for $100 you can get a very fast 1TB nvme drive now days, which is fine for 99.99% of the population.
Your use case of people running desktop with 100TB is niche, for $100 you can get a very fast 1TB nvme drive now days, which is fine for 99.99% of the population.