That's why I said, "on popular routes" (I probably should have said "on busy days" instead). When the number of available seats runs low, the price quickly surges from 22€ to 48€ (or even higher). 48€ vs 75€ with Bahncard 50 is not a huge gap anymore. 150€ also is for "Flexpreis" which isn't really a 1:1 comparison.
Comparing both pricing models isn't really that straightforward, which is why I left it out of my initial comment.