The PMs only have a 3-5 year term. They can't be taken from the companies that bid due to conflicts of interest, so they rarely are in charge of an area they have expertise in. How long would it take you to get enough technical domain knowledge in a new field to actually see through a professional PowerPointer that's polished their technological turd for decades?
There's supposed to be a set of contractors that the PM refers to for technical advice that also provide continuity over longer terms, but the pay is not really competitive (due to budget cuts) so there's more churn and less talent than there used to be.
I'm sorry, but this is basically incorrect on every point other than the limited tenure. Source: I work in this sector.
PMs often come directly from industry. Once they do, there is a period over which they are not allowed to make direct decisions that affect their previous company, but the previous company is free to bid on that PM's programs and speak with that PM. When these conflict of interest situations arise, the office appoints a delegate PM to make decisions associated with that company.
There are absolutely varying qualities of PM, but the majority of them would be considered a domain expert or subject matter expert in some technical area. Standard practice is for a new DARPA PM to inherit existing programs that are already executing as the old PM finishes their tenure. When a PM leaves, the office tries to hand the executing programs to a new PM who knows something about that field (or is an expert). That doesn't always happen, for various reasons, but they do try to do it that way.
There is a large contractor staff that does a lot of heavy lifting on both technical and programmatic fronts. The PM is the decision-maker, but the contractor staff are integral. These contractor jobs can pay quite well for senior staff or technical experts. Maybe not FAMANG software developer salaries, but particularly for topics in the physical domain, the salaries can be significantly higher than the equivalent role in industry.
Once upon a time I knew a guy who claimed to know people who took the second lowest bid, figuring the lowest build was full-on crank and the second was only slightly unhinged.
I didn't know that guy long enough to find out how that worked out for his friend long-term.
