Antiquities and heirlooms can be a good stable investment, the same reason people trade art or watches or guns or cars. Some of these are fun to use without reducing value.
So SV always had a community of very wealthy nerds who could afford a used PDP-10 and its insane running and maintenance costs.
But... the community was always very small.
And today, the number of people with that kind of money and a similar nostalgic attachment to increasingly remote history is even smaller.
It is only an investment if it (likely) gains yield. Otherwise it is just a means of preservation of value.
This is is the area I focused on. I'm now at point where I would rather shed objects than collect them. I will probably hold on to the rarest handmade objects. The mass produced from the late 70's to the early 2000's I would like to get rid of.