According to the Talmud, the final redemption will mirror the first redemption from Egypt. Only 1/5th of the Jewish people left Egypt.
Why did 12 million Jews die in the Plague of Darkness? They didn’t want to leave Egypt.
“The Exodus from Egypt liberated only one out of five Jews…because all those who were bound to Egypt and did not want to depart died in the three days of darkness and were not privileged to leave. Only those who desired redemption with all their hearts were redeemed. The Final Redemption, likewise, depends upon our yearning.” Ohr Yechezkel, Emunat HaGeulah