More Words, Deeper Hole

The description of how Polywell was supposed to work never made any physical sense. It was never subject to scrutiny in the peer-reviewed literature (this should be a screaming red flag, btw), or if it was, it failed to pass muster for publication. The results they did report (in non peer-reviewed venues) were very inadequate to support any sort of optimistic assessment, or to bolster the case on how it was supposed to work. Conventional fusion, even if it is impractical, is subject to scrutiny to keep the players more or less honest.

Rocket costs should fall faster than reactor costs because we are building a lot more rockets than we are reactors. Generally, small things improve faster than large things. For the same reason, distributed energy systems (gas turbines, wind turbines, PV) are improving faster than large fixed baseload plants.

As for Longshot: so the fission part was just a distraction? Ok. That's basically "let's pretend we have a pulsed fusion reactor with mediocre Q". Not sure what that really buys you anyway, particularly if it's a DT reactor and 80% of the energy comes out as neutrons, which are pretty much useless for propulsion.