It's worth remembering that most discussions like this are dominated by enthusiasts (including both of us) whereas most people in general are not enthusiasts.

In my experience, most people don't actively play more than 512GB worth of games at once, and you can add to this with spare microSD cards or other PCs on the network. Steam makes transferring game installs to the main SSD from elsewhere rather painless.

Even as a bit of a data hoarder myself, I only really go beyond 512GB to: 1) keep pace with multiple friend groups that like entirely different game genres I need to all keep available at a moment's notice, and 2) maintain games modded outside the Steam workshop that I may not play that often but still want to not have to set up more than necessary.