The "trekonomy" only works when everyone is onboard a starship and their cabin and their necessities are provided for them. Their "uniform" precludes fancy watches, gawdy jewelry, or anything other than replication of FUNCTIONAL ITEMS.
In the real world (sorry, fellow Trekies) people need HOUSING and the more $$$ you have the bigger the house. Houses sit on property. So if you're trying to get out of the NYC apartment and into a big Texas-sized house on a Texas-sized ranch, it's $$$.
People who are not in the military wear jewelry, and if you're a famous celebrity with no talent, it has to be big on the diamond front. You need $$$ for that, because even though manufactured diamonds are more perfect, they aren't "prized" as much as the flawed one we send people to the deaths in mines for.
- Fancy watches. You can't 3D print a Breitling. But if you could likely it would be prized less, just like diamonds.
- Cars. You can't 3D print a Lamorghini Gallardo or wrap it around a light pole because your $$$ exceeds your talent (see youtube).
- Planes. Kanye can fly on a private jet, but you can't 3D print one, and only $$$ will get you there.
Trekonomy is a cute concept, and I hope that lots of people spend $$$ reading it. ...because you can't 3D print a book you haven't bought...
Ehud Gavron
Tucson AZ US