Do tell, dont leave me hanging
Wait let me try and guess...
Is it because they see it as a supernatural one off event, where God actually comes and makes His abode in him? And think being born again is becoming a new creation?
Or is it because they count the cost when they make the decision, for instance it could cost them their friends, their family, or even their life and when counting the cost they see all they could have in the world yet they still choose heaven/Jesus at the expense of the world and worldly blessings?
Is it because they genuinely believe, God is a rewarder of those who put their faith in Him, that those who genuinely believe He will reward life to those who ask for it, and they become sons or inheritors from the moment of conversion?