Thats counter to their religion. They HAVE to die when they set it off or they don't get the ones they killed as servants in heaven along with their virgins. The entire islamic 'logic' of martyrdom is to ensure a place in heaven by sacrificing your life by killing infidels and the more you kill the greater the honors bestowed upon you. It's also their 'out' if they were islamic sinners as in you can lead a life of pure anti islamic values like drinking and eating bacon and such but all you have to do to redeem yourself in the prophets eyes is blow yourself up and kill infidels. Do that and all sins are forgiven and you go to heaven with all the perks. Fully 10% of all muslims believe in this and with almost two billion of them that means there are hundreds of millions of potential throat cutters and suicide bombers scattered across the globe. So a sure sign your migrant islamic friend is going to go crazy on you one day is if he professes to follow islam but he likes to go out and party with you. He is setting you up for the bomb.