There is no such thing as "self-radicalization". If he was part of a skinhead group 30 years ago, well I can tell you from being in the punk scene that racist tracts/zines and racist Hate music were they way this ideology was spread. There was no "chance" in this. Since then there are many groups whose publications carried on this tradition, like the Council of Conservative Citizens tracts. Once the internet became a thing most organizing and indoctrination happens online. The many factions that make of the "Alt Right" work very hard to bring new members into the fold or radicalize the "merely" bigoted or racist. I'm sorry, but I just don't understand what you mean by "self radicalization". These beliefs come from somewhere and are bolstered by the communities and groups that also hold them.