For we who live are always being given over to death for Jesus' sake, so that the life of Jesus also may be manifested in our mortal flesh. So death is at work in us, but life in you.
2 Corinthians 4:11-12

The faithful are more likely to face persecution than not, and those who persevere in faithfulness win converts to the faith and strengthen the weak. By losing a few mortal years in one life, a martyr potentially gains eternity for many others.