Was that huge 2017 Equifax data breach part of a nation-state spy scheme?

That massive Equifax data breach on September 7, 2017, shocked everyone, but a year and a half later, where the data of all those 143 million Equifax users ended up is still a mystery.
CNBC reports that the current prevailing theory is that “the data was stolen by a nation-state for spying purposes, not by criminals looking to cash in on stolen identities.”
Excerpt:
CNBC talked to eight experts, including data 'hunters' who scour the dark web for stolen information, senior cybersecurity managers, top executives at financial institutions, senior intelligence officials who played a part in the investigation and consultants who helped support it. All of them agreed that a breach happened, and personal information from 143 million people was stolen.
But none of them knows where the data is now. It's never appeared on any hundreds of underground websites selling stolen information. Security experts haven't seen the data used in any of the ways they'd expect in a theft like this — not for impersonating victims, not for accessing other websites, nothing.
But as the investigations continue, a consensus is starting to emerge to explain why the data has disappeared from sight. Most experts familiar with the case now believe that the thieves were working for a foreign government and are using the information not for financial gain, but to try to identify and recruit spies.
Good, gritty detail on the methodology behind the theory.
Read more: The great Equifax mystery: 17 months later, the stolen data has never been found, and experts are starting to suspect a spy scheme