As the DB (Deutsche Bahn) is a private company now (although they are 100% owned by the state), they have to make a profit.
How do you make a profit? Either raise prices or lower costs. Doing both is the best and that's what they do. Raising prices is easy, it just gets more and more expensive, even the "cheap" Deutschlandticket is too expensive, experts say it should probably be around 29 Euro/month to make a real change.
How do you save costs? You do only the bare minimum of maintenance, don't invest in building more tracks and instead reduce tracks and track switches. That's what they've done the last 20 years or so. [0]
This leads to ICEs being stuck behind slower trains as there are simply no more tracks to switch to and pass cargo trains etc. So, if some train gets stuck somewhere or has a defect, every other train is stuck behind that for some time.
Now, as the state subsidizes some parts of Deutsche Bahn, building something new is also cheaper than maintaining what is there. So they let some things rot down so far that they have to rebuild it completely. As the subsidization is then higher, that's better for the turnaround numbers.
There have been thoughts about splitting off building and maintenance of the tracks completely of the rest but that didn't work so far. In that scenario the state would take care of the infrastructure and DB would just "rent" it to drive on it.
To add something else to it:
I think David Kriesel has it in his talk [1]: DB also "found out", that you can reduce delays in your overall network when you start skipping stops or canceling them completely. If you know that you're too late at your last two stops, just cancel those stops completely.
Cancelled stops are not part of the delay statistics of DB, so not driving somewhere at all is, statistically seen, better than arriving there late. Only a little bit problematic for the people that want to get there or board there.
Turning around early also has the "advantage" that your new train will be back on time again easier.
As the DB (Deutsche Bahn) is a private company now (although they are 100% owned by the state), they have to make a profit.
How do you make a profit? Either raise prices or lower costs. Doing both is the best and that's what they do. Raising prices is easy, it just gets more and more expensive, even the "cheap" Deutschlandticket is too expensive, experts say it should probably be around 29 Euro/month to make a real change.
How do you save costs? You do only the bare minimum of maintenance, don't invest in building more tracks and instead reduce tracks and track switches. That's what they've done the last 20 years or so. [0]
This leads to ICEs being stuck behind slower trains as there are simply no more tracks to switch to and pass cargo trains etc. So, if some train gets stuck somewhere or has a defect, every other train is stuck behind that for some time.
Now, as the state subsidizes some parts of Deutsche Bahn, building something new is also cheaper than maintaining what is there. So they let some things rot down so far that they have to rebuild it completely. As the subsidization is then higher, that's better for the turnaround numbers.
There have been thoughts about splitting off building and maintenance of the tracks completely of the rest but that didn't work so far. In that scenario the state would take care of the infrastructure and DB would just "rent" it to drive on it.
To add something else to it:
I think David Kriesel has it in his talk [1]: DB also "found out", that you can reduce delays in your overall network when you start skipping stops or canceling them completely. If you know that you're too late at your last two stops, just cancel those stops completely.
Cancelled stops are not part of the delay statistics of DB, so not driving somewhere at all is, statistically seen, better than arriving there late. Only a little bit problematic for the people that want to get there or board there.
Turning around early also has the "advantage" that your new train will be back on time again easier.
It's a mess for long distance travel.
[0]: https://de.wikipedia.org/wiki/DB_Netz#Netzentwicklung [1]: https://www.youtube.com/watch?v=0rb9CfOvojk