DARPA is about a close to venture capital operation as you can get in the DoD or the Fed gov.
But it still isn't actually close.
If you are a technical whiz, then inside DARPA, or in some actual venture capital enterprise in the real world, things might be very similar. But for an executive, things are very different. A VC exec needs to raise money, schmooze rich people who can smell BS a mile away, and appear to have profits just around the corner. Within DoD, things just aren't done that way.
The key skill: can you follow a rigid bureaucracy? Sure, your tech people don't have to -- they are the whiz kids. But the management? Believe me, it's allllll about the bureaucracy. VC execs live outside that world.