Is knowing another language a benefit or a liability?

We met with the daughter of a Holocaust survivor from Thessaloniki. She shared the story of how her father survived because his family spoke Greek AND German. As the Jewish families were brought to the train station to be transported to concentration camps, her father and her grandparents translated the instructions from German into Ladino. Is that survival? What an impossible position to be in! On the other hand, we heard stories of people being killed because of their Spanish accent when they spoke Greek. They were killed because their knowledge of a second language made them stand out! I’m constantly looking for reasons to motivate my students to learn Spanish. Which argument do I add to my ‘List of Reasons to Learn Spanish’? The ability to protect yourself from death by assisting the enemy or being killed without question just because of an accent from your native tongue?