Afghanistan’s professional class of men and women, part of a generation that came of age under the shield of the U.S. military, are weighing the danger of rapidly advancing Taliban forces. Many are packing their bags.

Hasiba Ebrahimi is already gone. The 24-year-old actress, who embodied modern Afghanistan’s optimistic youth, was raised, like many Afghans, as a refugee in Pakistan and then in Iran. She returned to Kabul in 2014 and has since become a star in the country’s new film industry.

In a video released in November, Ms. Ebrahimi urged young Afghan women not to lose hope: “Everything is hard, but nothing is impossible.” She traveled to Australia soon after—for what she thought would be a short reunion with her New Zealand-based sister. She is still there.

“My mom is telling me, ‘I am begging you, I love you so much, but I can’t let you come back, I can’t let you put yourself in danger,’ ” Ms. Ebrahimi said from Sydney. “We have all had hope. We were thinking that we would do something out of that country, working harder and harder each day. It’s really sad to think that you don’t have any future in your own country.”