Board Thread:Boruto Discussions/@comment-3261234-20161118110518/@comment-9782468-20161208232543

HahmezHiraishin wrote: Boruto's rasengan dissipates because of an abrupt change in chakra nature into pure wind chakra....If u notice Boruto's ability to learn the rasegan more quickly was partially due to him using both of his hands, by doing so one hand forms raw chakra whilst the other applies the elemental affinity( albeit subconsciously) Rasengans in general cannot be thrown, however we saw where Konohamaru could launch a sealed rasengan using the kote.....To date Boruto is the only true user of the rasengan who is able to throw it, there's no debating whether or not he is a prodigy...he just lacke all motivation and also due to Naruto ignoring him he didnt really believe he was strong enough on his own because of his desperate attempts to be acknowledged by his dad.

His mastery of 3 elemental affinities without training shows he has extraordinary talent alone..........If u notice noone was surprised by his feats with the kote but they were apalled after learning he cheated. If he was just a good for nothing, he would have been snuffed out from the very beginning by if not everybody else his own team mates and sensei It doesn't dissipate to pure Wind Chakra, otherwise Momoshiki would see the chakra with his Byakugan.

The speed that Boruto learned the Rasengan wasn't because he used both hands, since Naruto tried using both hands for awhile too. Boruto learned fast because he's a prodigy.

Boruto is not the only true user of the Rasengan, he has nowhere near the control that any other Rasengan user has shown. He just threw his Rasengan and didn't realize he had applied Wind Nature to it. When the chakra of the technique disappeared, the wind kept going with the force of the Rasengan without the chakra.

He definitely trained to be able to use three elements and I doubt he's mastered all three.