Rambam in Hilchot TeShuva says that all the Prophets commanded the people to do TeShuva, and Am Yisrael will be redeemed only through TeShuva. Rabbi Yaron Reuven says, MaShiach is coming soon and most people aren't ready. During the Exodus of Egypt a minimum of 80% of Am Yisrael died in Egypt during the Plague of Darkness, and only the ones that survived were those that did TeShuva.