Everything you said applies today to the demographic pyramids of the respective 2 countries, with only an 11 years delta. And yet Germany has 5x the GDP.

https://www.populationpyramid.net/turkey/2019/

https://www.populationpyramid.net/turkey/2030/

https://www.populationpyramid.net/germany/2019/

https://www.populationpyramid.net/germany/2030/