HDG wrote: ” The only explanation that I heard to be machria is that the Galut ended after 70 years, but that it took a very long time (165 more years) until Bayit Sheni was built. “
This is refuted by Ezra 3:12 describing the old men who still remembered the first bais hamikdosh weeping seeing the second bais hamikosh.
According to your theory, they would be over 200 years old !