I think we got a lot more insight into Kylo's fall than most people realize at first glance. I think Finn and Rey are supposed to be obvious foils to Kylo, and Anakin's fall a prototype for Kylo's fall.
Anakin has a great destiny thrust upon him by the Jedi, who believe him to be the Chosen One and are trying to train him to achieve their expected outcome of the prophecy. Though he eagerly accepts Jedi training, we see that his priorities do not necessarily align with the Jedi: he wants to come back to free his mother (and earlier he expresses the expectation that Qui-Gon would free all the slaves). Once Anakin decides his alignment with the Jedi constrains his own personal agenda - both his desire to save the people he loves and his belief that justice can brought to the galaxy by "someone wise" who will enforce peace - he turns on them.
Likewise, Kylo is conscripted into Luke's Jedi school, also presumably not by choice, and probably not with a clear agreement on the agenda that underlies his training (to keep him on the path of good, which would naturally be against his impulses if Han & Leia were worried there was too much of Vader in him). This makes him very susceptible to being seduced by outside influences that purport to give him greater agency: like Snoke. Since he has no real control over the direction his life is going based on the circumstances of his training, he's able to be persuaded to turn against his teacher, as well as the far-from-perfect family that sent him there, to take control of his own destiny.
Finn goes through a similar character arc, but in the opposite direction. He's conscripted into the First Order from birth, and eventually comes to realize that what he's fighting for isn't right. He makes the choice to leave - the first time he's ever able to exercise a real sense of self. He is symbolically named by Poe at the same time to show that he is no longer just a number, but a complete human being.
And Rey faces the exact opposite circumstances that Kylo does. She isn't forced into Jedi training; she's left to her own devices and makes a conscious decision on her own to take up the lightsaber and let the Force guide her. Thus, she's put in a position of total agency about her affiliation with the Force. In the end, her journey to Luke represents her acceptance of the Force and the path of the Jedi - a path that she chose for herself.
