When Jesus told them that the temple would be destroyed, they misunderstood and assumed that he meant that the whole world was coming to its final end. After all, the temple was their world, their theological framework, and their faith foundation. If the temple was on the verge of destruction, then they naturally felt that meant that history was finished, the kingdom was about to break in, and there was nothing left for them to do but sing psalms and wait for God to gather them into the heavenly places. Not so said Jesus. Wars take place, famines happen, tumult occurs.
Loved ones die, jobs end, dreams vanish.
But according to this gospel reading, such is not a time for passivity or a time for despair. Instead, put on your white robes and get ready for the End is approaching. Pieces of the world will always be coming to an end. Do not go after them, and do not be afraid. Indeed, Jesus says, by such endurance you will gain your lives.