Board Thread:Theories and Speculation/@comment-30736821-20170426173032/@comment-5085906-20170428223415

Whatever the chakra spirit is, it seems to prey on people's subconscious desires (Denki's desire to stand up to his bullies, Lee's desire to be more confident). This is why Kawaki can't be Iwabe - cause Kawaki seems to bear hatred for the shinobi system while Iwabe wanted to spin the wheel and take it 12 years back, in a time when it was even more shinobi-centric than it is during Boruto's timeline. So, there's a clear contrast in their motivations.