China is probably the best case scenario for high speed trains. They have high population density to support train networks, virtually no opposition from NIMBYs, and low construction costs. Yet high speed trains there operate at a loss[1], and airplanes are still competitive there. If high speed rail doesn't work there, how could you seriously claim we should switch all air travel to high speed rail?
[1] https://en.wikipedia.org/wiki/High-speed_rail_in_China#Profi...