Can you think of examples of this cycle? I know this is roughly what happened with mainframes, but I struggle to think of other times it went like that.

Maybe arcade games?

The first one was code breaking. The most recent was "cloud". If you look you will probably find others.

cloud? I feel like that's an example of things going the other way. It used to be every company would have either on on-prem or a colocated server at the nearest network hub - a fairly de-centralized system, and then everything went centralized with cloud platforms.

CGI rendering. To do Pixar quality animations you used to need racks and racks of servers and it still took months. Now anyone can do it, and we saw tons of slick animations on YouTube from indie studios as a result (before the AI slop cloning started I mean)