I like airplanes. I really do. Someday I'll fly one myself. But beyond that, air travel has it's own set of problems. Each airplane "ride" has this annoying process called "boarding and deplaning". It's the whole reason why you have to show up 1 hour early to the airport, and while your flight arrives at maybe 2pm, it still takes you 30 minutes to be on your way out of the airport. And that's all IF things go smoothly. Chances are a bag gets lost, somebody holds up the security line, etc.
No matter how hard you try, you can't argue against that. A transfer in a large sized airport will need at least 1 hour to make it assuming things go well. But usually you plan on a 2 hours between transfer just incase you're delayed for whatever reason. It doesn't matter where you are, this seems to be the norm all over the world for air passenger travel.
A train transfer on the other hand can be as short as however fast you can run to the next train. There's also none of that take-off and landing stuff. You can even line up outside the door as the train comes to a stop. A ticket purchase can also be made minutes before the actual departure. It is quite a trip to see a good working train system in action. I recommend it. We don't have much of it here in the states.
Now on the to the cost. There are certainly a lot of dumb reasons why the California HSR project is getting inflated. It basically boils down to two groups that I'll call "Not in my backyards (NIMBY)" and "Please in my backyard". The first is easy to explain, but it is mainly rich people and people like yourself that think the project is useless. So these people band together to prevent any meaningful progress happen. I'd say their strategy is akin to that of the GOP's strategy in congress (whine as much as possible so that nothing gets done). Rich people obviously don't want the project because it will change their communities along the proposed track lines. People like yourself don't want it because you don't think it is economical.
The strange thing is the farmers and small towns along the valley DO want the train. In many studies when HSR is built, small towns that get a trains stop actually see population and economic growth due to more people having access to the town. So this becomes a lot of bickering and whining for stations, some which may not even be worth the hassle in the initial segment.
Finally there's a lot of freight companies and FRA standards that make absolutely no sense. Not only does this affect HSR, but it also affects local passenger rail services. Our passenger rail trains are generally overweight due to "safety" rules enforced by the FRA on minimum weight.
So if you combine all of those factors, what we have is a lot of unnecessary needs to address factors just so that everyone in their municipality or interest can benefit. That means unnecessary tunneling where it is perfectly viable to be at grade. Unnecessary extra tracks. Unnecessary stations. Unnecessary train specifications.
But of course people like you have to make this political, make it black-and-white. "There is no viable HSR system" is obviously not the case when the rest of the world continues to expand passenger rail services. This project is obviously overweight, I agree with that, but let's at least understand what's wrong rather than fill it up with logical fallacies. It's quite obvious that's how many things are working out in this country. Everyone seems more interested in throwing up own straw-men rather than working together to do what's reasonable.
Fun observation, the interstate highway system is probably the most expensive public works project in history. Should that have been considered a boondoggle? From wikipedia: "The initial cost estimate for the system was $25 billion over 12 years; it ended up costing $114 billion (adjusted for inflation, $425 billion in 2006 dollars) and took 35 years."
If I had to run the project I'd certainly look at implementing a shorter initial segment with less opposition. LA-Vegas would be quite profitable in my opinion. If it was only CA, perhaps SD-LA would be a possibility despite both cities being car centric.
I also wouldn't mind more local passenger rail investment instead of HSR. But nobody seems interested in public transit either. Arguments against public transit are usually "it stinks" and "there's crazy people", yet in normal circumstances, public transit works well in other countries because the "normal" people outnumber the crazies and they have sane cleaning procedures or culturally enforced rules (mainly don't be a douchebag on the train). Meanwhile we seem to be perfectly happy to have people that are clearly not qualified to drive a car on the road every minute of the day. So instead of communicating directly to the other person, now you can scream at your windshield and drive like an asshole.