It's quite successful in Europe
For example; in the UK on London -> Edinburgh, Caledonian Sleeper has on average 250 passengers per day (but this is the entire route - not just london to edinburgh). Given there is roughly ~2tph throughout the day for about 16 hours a day, each with ~1000 seats (with very high load factors), that's about 30,000 passengers/day on the "day" train. Probably roughly that again flying. Plus driving and coaches and it is absolutely tiny.