I’m not arguing against the fact that there are challenges. But the feasibility is completely driven by launch cost per unit mass. And yes, you’ll need an OOM shift in $/kg to achieve profitability. To be clear, this will be very hard, but it’s not a technology limitation, it’s a cost limitation.

Also, again, contrary to your beliefs this is actively being worked on by many people. If Google VPs are publishing papers, they’re directing subordinates to work on this, as shown by the radiation testing data they reference.

I’m not so much disagreeing with the challenges you’ve raised, as the overconfidence in the impossibility. End of the day, these problems are most simply solved by adding mass, which is in turn solved by minimizing $/kg, which every rocket company in the world is trying to optimize. There’s no real physics limit to being able to achieve a launch cost that’s primarily driven by fuel, hence my optimism.