>With the cost reduction opportunities of mass production, I don't see why they should cost more than $500.

I think it's more of a supply and demand thing. People spend a lot on their hobby. And it's not as much mass produced as some other items.

With a large percentage of the population drinking coffee on a regular basis, can you really call it a "hobby"?

Yes. I have briefly encountered the real coffee nerds. They are extremely serious and meticulous about their coffee, do actual science, and, I am sad to say, the coffee was better than any coffee I have had before or since.

You will not get coffee that good from a coffee shop, it isn't economically viable. But the technology exists.

Arguably for "coffee geeks" it is a hobby!

I'd assume the coffee geeks have figured out how to make cheaper machines and put the designs on github.

They have, kind of. Check out Gaggiuino. Sadly not really open source (Gen3) but you can get a cheap $500 Gaggia Classic and add fine grained control with an Arduino and display: https://gaggiuino.github.io

Then there's the really open source Rancilio PID Clever coffee project:

https://github.com/rancilio-pid/clevercoffee

Different machine, similar approach, a bit more DIY since you can't buy a kit.

Would two DeLonghi Dedica machines count as dual boiler?

Ha, this entirely proves my point that these dual boiler machines can be cheaper!

Maybe material cost? I have a lelit mara machine, it’s pretty heavy. It weighs 18kg, with a plenty of brass and copper pipes. Also the internals don’t look like it can be machine assembled an the fat that it’s made in Italy makes it more expensive in man hours