Sorry, I intended to explain that later in the comment, but got distracted and then just submitted without re-reading.
The flight time is nominally ~2.5 hours, but many/most planes leave late, meaning the actual flight time for the passenger (time between scheduled departure, and actual arrival) is >3 hours.
And airport security and boarding takes longer than train security and boarding. So the time saving isn't all that much vs. the fast train.
If you look only at the stated (=named) departure and arrival times, the plane looks much faster (nominally). If you consider that you need to be at the airport at least 1h before departure, and frequently airports are outside the city centre while train stations are in the city centre, that nominal advantage shrinks considerably.
http://www.dictionary.com/browse/nominally