The DB is and always was fully owned by the government, this is not the usual case of "dumbass executives mess things up".

Unfortunately, the DB first got hit by Thatcherite neoliberalism in the early 90s that led to "unprofitable" things like switches, railyards or lesser-used routes to be torn down and the real estate sold off (to prepare for a privatization that THANK GOD never happened), and then we got 16 years of Conservative traffic/infrastructure ministers whose job priority was to funnel money to Bavarian highways [1], not towards railways.

Unfortunately, while the left wing loves to prune its ranks in purity tests (partially because its voters demand accountability), the Conservatives have a solid "better dead than red" voter base.

[1] https://www.merkur.de/politik/csu-parteitag-bayern-markus-so...