I think alot of kids from bt parents go off mainly ’cause they don’t feel welcome in the frum society. They don’t feel that they belong.. they think that if they go off the derech they will be more accepted in society. But they are wrong. Kids that go off don’t belong there and they certainly take one big step away from becoming accepted into the frum society. In every circle, even the nonjewish circles, social habbits are naturally the same. If you cant win here you certainly won’t win there. so you might as well follow the torah and love hashem. they say but really truely loving hashem and serving him with your full heart and soal, everything will go right for you. Hashem put you into this world and if you internalise the fact that noone can help or harm you other than hashem then you will fall away from the resentment of other people once you do that you will start actuall seeing the good in others, and you will start to like them once you truly love them they will love you back and you won’t feel the need to want to escape your familiar society that you grew up in…
personally I can tell when people go off the derech , or if they were just simply raised that way, just like you can tell who the Bt’s are… if you know what i’m saying. Tell this to him and have him watch the shiur and he will definitely change for the good. kids that are burnt don’t see past thier noses, so you have to tell him whats beyond the nose!!!
Good luck and I really hope he changes is ways!!! It will be better for him in the long run, and he will live a much happier life. He may think that the grass is greener over there however in actual fact it most definitely is not.