Once the land is purchased, levelled, and conditioned you now have a space that can have trains running on it for the next fifty, one hundred, or more years. Look at the UK's railway lines, some of them have been operating for two hundred years and counting.
This type of short term thinking is why infrastructure spending in the US is at an all time low. Instead of spending for tens of years into the future, we only evaluate the costs relative to the next five years and therefore make decisions more valuable to tomorrow than next week.
Once CA buys this route, they own this route forever. And in a state gaining more and more people every day, cutting out land for infrastructure is only going to get more painful in time.