Since 1958, it has been a driving force in the creation of weather satellites, GPS, personal computers, modern robotics, the Internet, autonomous cars, and voice interfaces, to name a few.
This fascinating and thorough article, or more precisely a self describe “collection of atomic notes”, attempts to explain why DARPA works in search of creating a private sector funded “ARPA”.
The section on program managers is worth a look as the characteristics described there are also those that make good investment analysts.