Who is gonna lose big is flight, on that route. 4h one-way is comparable to flight... 1h10m flight time, plus 1h getting from Munich city center to the airport, plus 1h of pre-boarding time plus another ~45min to get from Schönefeld or Tegel into Berlin plus the inevitable delays on public transport, and suddenly the train is a viable alternative.
Also, in a train you usually won't end up with damaged legs or other flight related issues and you don't need photo ID or be treated like you're a terrorist (patdowns/searching, in addition that your PIR records WILL end up at NSA HQ, no matter what), which is the reason why I do not fly.