People are feeling all kinds of pressure these days. If they want to have kids they need a lot of resources. But having a lot of resources is really difficult to do when you’re young. So that naturally suggests a compromise: one old with resources and one young with health.
People make life choices based on how things are, not how they ought to be.
Generally a “gold digger” refers to a young woman who marries an elderly rich man with the intent of gaining a large inheritance, not a young woman who marries an established (but still working) man a few decades her senior with the intent of raising a family. A big “gold digger tell” is that the rich guy already has adult children who end up in a feud with his new young wife (because she represents a threat to their inheritance).