The main reason that Europeans fly (including Brits) is that it's simply the cheapest option, more-so that bus in many cases. Airplanes are pretty much providing services similar or lower than to buses, and trains tend to have better service and also tend to be more comfortable these days. Most airplanes have been reduced to low cost or no-frills status, even the full service ones, and flying is a nightmare in terms of peace-of-mind and comfort.
Deutsche Bahn is one of the better railway operators in Europe, especially compared to the railways in Southern Europe or the UK, but obviously there are a lot of improvements that need to be made.