There were other internetworking projects at the same time as ARPANET. The DoD's tech was better, and to people like the IETF, "better tech" is all that matters in picking a standard. But most of the people driving the adoption of internetworking among large corporations and organizations weren't DoD people, or even people with a defence mindset. They were just sysadmins, librarians, and communications engineers trying to freely peer their networks with other networks, adopting whatever standards came along that would allow them to do that. Such folk worked on their own standards (see e.g. MIT's Chaosnet) but chose to switch over to the [IETF standardization of the] ARPANET stack when it became clear that's where the future was.

Precisely this. The Internet was born out of the dreams and efforts of many nerdy people who had no reason to do it other than it could be done, and nobody had done it before.

That reasoning drove the majority of computer technology progress during the 1980s and 1990s. It wasn't until AFTER the birth of the World Wide Web did mainstream businesses start to really look at monetizing this new market, and in a symbiotic way hackers and nerds and geeks started crowing about altruistic philosophies like decentralization and how information "wants" to be free.

To answer both of your points, fast was implied by virtue of it being a communication network.

The open part can be pedantically removed in the case of ARPAnet, but I've not met anyone who confuses the Internet with ARPAnet. The Internet, as it came to be called in the 90's with the rise of the World Wide Web, WAS at it's core 'open'. Pretty much everyone I've met who was around and working on the ARPAnet saw it as a foregone conclusion it (a network based on the lessons learned through ARPAnet) would be going public in one way or another.

> but I've not met anyone who confuses the Internet with ARPAnet.

Now you have! :) Unless you don't count online interaction.

In particular, to guarantee a devastating response to a Soviet first nuclear strike. As I recall.

You're referring to ARPA net, which is not "The Internet".