Peter began to say to him, "We have given up everything and followed you." Jesus said, "Amen, I say to you, there is no one who has given up house or brothers or sisters or mother or father or children or lands for my sake and for the sake of the gospel who will not receive a hundred times more now in this present age: houses and brothers and sisters and mothers and children and lands, with persecutions, and eternal life in the age to come. But many that are first will be last, and (the) last will be first." (Mk 10:28-31)
Anyone who gives up material wealth (houses and land) and relations (brothers, sisters, mother and father) for the sake of Jesus and for the sake of the gospel is rewarded. Jesus and the gospel should be preferred to anything else in the world. One should be ready to lose even relationships for the sake of the gospel and Jesus. Among the relations, one should be ready to give up the past (parents) and the future (children). So, one should be ready to give the past, the future and the present (material security)
Whatever is lost is not lost for ever. What is lost is gained hundredfold (strange!!!). He receives the past, the present, and the future, a hundredfold. This is the way God works. But God also promises persecutions. This is the sign of a follower. This is the share that he has from the master. The master met with persecutions, so also should the follower be.
The greater reward is the eternal life. Eternal life, here, according to this evangelist, is something that will happen in the age to come. So, besides the present security, Jesus, promises persecutions and eternal life. Yes, lost is a gain and persecutions will lead to eternal life.