I suspect that I'll only ever buy another 3 hard disks in my life. I need to buy three at some point to upgrade the 2TB drives in my home Linux ZFS server (probably with 4TB drives).

But after that, I fully expect SSD prices to have come down enough (and my storage need increases to have continued to slowed) to mean that by the time I need to replace the 4TB drives I'll be able to do it with SSDs.

I only have 5 actual hard drives in use now, the three in my server, one in an old Mac Mini (which has a spare SSD waiting for it when I get round to it) and one in my gaming PC. All the drives I use for work daily are SSDs.