Sadly, the economics of this will never work out.
I ride BART and Caltrain multiple times a week. Trains are delightful. And so are planes.
It typically costs about $100, and takes an hour to fly from SF to LA. The train will be slower and almost certainly more expensive. Where is the benefit?
Long distance trains work in Europe because they are supported by a rich network of public transit options stemming from city centers, and a population that uses transit frequently.
But California public transit is a mess. When you rock up at LA Union Central and want to get out to say, Newport Beach, it's another three hours of navigating buses and the metrolink.
The money would have been far better spent integrating agencies and building out high speed rail in our urban areas. BART should be running out to Sacto, Stockton, Silicon Valley, and Marin. Requisition the Amtrak line and build a highspeed rail from San Diego to Santa Barbara - now that'd be something.
This HSR line makes a good deal of sense if it could be built. Your analysis of flying is wildly incorrect. The train will be faster door to door than the average flight.
But the main benefit will come from massive secondary economic growth. Cities along the line will experience dramatic increases in demand and economic activity. Cities at the terminus will have a massively increased share of workers in the commute threshold.
Further, the HSR line serves as a backbone for future lines, tying the state together.
The plan is very good on paper. It’s getting creamed in implementation because CA is not politically aligned on this project. Half the state doesn’t want it to succeed at all.