HSR is not "public transit." Public transit helps lower-income people commute to their jobs. Lower income people don't travel regularly between SF and LA--they have no need to. They might do it occasionally, but they don't do it often enough where the convenience of a train is going to mean much if the train isn't any cheaper than flying.[1]
The folks who really benefit from HSR are business travelers. They're the ones who need to travel city center to city center regularly. They're the ones who really have a reason to prefer taking a train, because they can work more comfortably en route.
[1] Also, the target price ($86 one way) is a completely fantasy. At that price, it would be one of the cheapest HSR trips per mile in the world. https://nextcity.org/daily/entry/fare-cost-ride-california-b.... There is no way California is going to run the cheapest anything.
That money could be so much better spent in ways that have an actual impact on lower income people.