what is reason that suicide bomber agree to blow them self’s?

Answer 1

The data collected on all suicide attacks since 1980 by Robert Pape of the University of Chicago found that overwhelmingly suicide-terrorist attacks are not driven by religion as much as they are by a clear strategic objective: to compel modern democracies to withdraw military forces from the territory that the terrorists view as their homeland. For exampe, in Lebanon in the 1980s, of 41 suicide attackers, only eight were Islamic fundamentalists. Twenty-seven were Communists and Socialists. Three were Christians.
http://www.amconmag.com/2005_07_18/article.html

Answer 2

Because most of them are Muslim. And they are willing to die for Allah.