Well, yes, if you go full enterprise with 6 VM's and 30 Docker containers I can understand how you'd aim for 64GB of RAM but then, why would you want to use a fanless mini PC for it?
https://www.ahead-it.eu/en/shop/servers/embedded-iot/intel-a...
Those?
Technically they are fanless but I wonder how well they would work outside of a rack with high ambient, they seem to be fanless themselves but still rely on having plenty of air pulled across the casing. Mounting them vertically might work. 850 euro though!