Because we are or were in a abusive religion that we were manipulated to believe had our best interest at heart ( everlasting future etc) with constant control meeting , assembly's , shepherding etc ,we almost stopped thinking for ourselves and manipulated to share it with others that JWs were chosen by god to share the good news and then could not fully understand why people could not see it also , so they were not worthy of the benefits of the kingdom.
It's like why do people stay in a abusive relationship ,why don't they just leave , even though they feel or know something isn't right because their abuser has manipulated and controlled them that they know what best for them and they have their best interest at heart.