The topic can make or break a dissertation. It convinces selection committees, helps earn financial support, and steers a career in the right direction.
A doctoral degree will certainly only help you to become rich in an idealistic sense. The first contract for a PhD position should have a term of at least one year - after which, graduates are rewarded with their first salary increase.
Freiburg is an important centre for academia and has a number of top notch research institutes to its name, as well as an ancient and internationally respected university which excels both in the sciences and humanities.