> Probably many are, but for a person crazy enough to do such a horrible act such threats would also likely not work (either "nothing to lose" or "don't care about anything anymore").
War isn't crazy, and participating in attacks on [your country] doesn't mean that one is irrational or doesn't care about anyone in the world. Just because you are willing to give your own life for a cause doesn't mean you have nothing to lose.
The reason I say it works is because it actually works, and has been used by states many times, esp. in South America by US trained torturers, but also by plenty of others, like the Khmer Rouge. The point is credibility - and if somebody has planted a dirty bomb in some city, you can't credibly give them any reward for telling on themselves. You can promise things, but they will not believe you. If you're Pinochet, though, you can credibly threaten to have someone's children raped and murdered, because he did it all the time. He can credibly promise to do it even after the bomb goes off, and after you've been executed, because he's done it to others. He can have them brought to you and have it done in front of you.
The US also uses this tactic, although since it will never carry it out (although it will carry out deportations, indictments, etc. for family members) it relies on a lot of playacting. There are stories of the US pretending to torture family members within earshot of people being interrogated.