I would say "Twenty dollars a week doesn’t go far. Expenses had been greater than she had calculated. They always are."
Explanation:
In this answer, it explicitly says " Expenses had been greater than she had calculated. They always are." which infers that by saying "they always are", would imply she never makes enough money to be financially fit.
It is possible to have too much of a good thing because sometimes we can’t handle good things all the time. So I do agree that we can possibly have too much of something and not know how to appreciate it.
