I build windows software, so need Windows and VS. I keep my entire development environment in a virtual machine. I also have a couple of other VMs for client isolation, clean installation testing, etc.

So having that much memory allows me to run more than one virtual machine at a time, and keep enough reserve for my actual desktop.

It was also my first rebuild in over 12 years, and RAM prices hadn't gone stupid yet, so I figured I'd drop a few more $ and build another decade+ future proof machine.