In my opinion, there are worse ways for governments to subsidize aerospace and materials research and development, improve the connectivity between nations, generate national prestige, give people optimism for the future, and so on. 2 billion doesn't sound like a lot. It's a drop in the bucket compared to US military expenditures.

If California High Speed Rail loses a little bit of money, I won't be too upset by it. Unfortunately the up front costs are much higher, but at the same time, massive, massive infrastructure development is happening in California all along the length of the state, and the government is acquiring the rights to develop public transportation both now and into the future on that land. Again, there are worse ways to spend the money in my opinion.