They as a martyr and will enter Jannah. There is a hadith where it says if they had the chance they would go back on earth and get themselves killed again to experience the joy of Jannah/martydom all over again. Sometimes their are knowledge we can't fully comprehended but has benefits at the end.if you can read obviously you would know why some people have doubts the people inside Mecca trusted allah but that didn’t stop the Qaramatians from killing all around the Kaaba and the Muslims did not fight them BELIEVING that Allah would save them...but he did not what type of god would see his people die and suffer like this knowing in the Quran allah says do not fight in the Kaaba as I will protect you