How was Corrie able to survive while Betsie was not?

At Ravensbruck, the sisters experience positive things, like being together in the mornings and evenings. Corrie understands getting the Bible past inspection as God’s provision. In addition, the fleas symbolize the benefit of looking for good during dismal situations. Moreover, the tiny insects reveal how the National-Socialist philosophy of worth and value fails to view the world. I don't think Betsie is as "street smart" and aware of practicalities as Corrie.