In Little Women, why were the March sisters miserable at the thought of their monetary condition?

The March sisters are incredibly unhappy about their financial position because it means that the two older sisters have to work and none of them can afford the things they want to have. Meg has to take care of a family of children while Jo works as a companion to her aged and infirm (and unpleasant) Aunt March. Neither of them is happy, and both feel totally put-upon by their responsibilities.
Their father is serving as a chaplain in the Civil War, and the girls must help to support the family because he had lost all his money years before, though the two eldest do remember a time when things were easier, financially, for them.
Meg would like to own pretty things like dresses and gloves and shoes, while Jo would like to have books and more books. Beth doesn't ever want for very much—she's the family's angel—but Amy wants pretty things as well as art supplies. The girls really can't get anything they want, and this depresses them, especially as it's Christmas when the book opens.