My first laptop in 1998 had a 2.1GB hard drive. Now, we have 20TB hard drives and there's more to come:
Seagate recently published its long-term technology roadmap revealing plans to produce ~50 TB hard drives by 2026 and 120+ TB HDDs after 2030. In the coming years, Seagate is set to leverage usage of heat-assisted magnetic recording (HAMR), adopt bit patterned media (BPM) in the long term, and to expand usage of multi-actuator technology (MAT) for high-capacity drives.
Seagate and Western Digital have been looking to radically increase sequential and random performance of HDDs by installing more than one actuator, with multiple read/write heads into one drive. Seagate's Mach.2 technology — which embraces two actuators — can almost double IOPS-per-TB performance of a hard drive and substantially increase its sequential read/write speeds.
Soon, we'll have mainstream SSDs with sustained transfer speeds of two gigabytes per second. Most hard drives manage only 10% of that. They're basically separate beasts. Nowadays, one should get both for the desktop: an SSD for the main drive and the hard drive for extra storage and backup. However, for most laptop buyers, solid state disks are a superior choice because of speed. Plus, who wants to carry around a slow 20TB drive in their laptop anyway?