Keep in mind there’s only about 50 miles of high-speed rail in the U.S. so far. With major cities like Dallas and Houston or San Francisco and LA still unconnected by fast rail, there's significant room to boost GDP and improve lives. Expanding rail isn't just about GDP growth, it's about enhancing daily living and connecting communities more effectively. As RFK famously noted, GDP measures everything ‘except that which makes life worthwhile’. Rail development does both, supporting the economy and enriching our lives.
Almost nobody will take that train daily, and it is stupid to think anyone would or should. However it is reasonable to expect the train will be crowded from all the people who take it less often. Companies send their people to other cities often for various business reasons. People take several vacations per year. Nobody is doing this daily - but the sum total of weekly, monthly, yearly, and once in a lifetime trips add up to a lot of people very day.