Long distance bus are much cheaper, but also much less comfortable and less reliable. DB gets a lot of flak for one hour delays on the first snow, my bus was delayed 3 hours at the start of winter. In general delays seem much more frequent with the bus. The concept of connecting to a different bus also doesn't exist (probably because of unreliable travel times), meanwhile with the train I can travel from anywhere to anywhere.

I would love cheaper trains, but they are already cheaper than traveling long distance by car and much more enjoyable and reliable than long distance bus. They lose badly to cheap flights though.