> That is, you can have a bunch of software developers (or miners), but if there is no gold to mine, they'll just sit idle (and eventually disperse).

not sure this is a good example - while it's true for actual gold mining, in the case of software developers, having other software devs around (plus also good computers, which you could argue is like gold) can be an opportunity in itself - look at all the devtools startups that happen in the Bay Area.

A large group of people is an opportunity in itself.