Are there any studies about radical ideologies and leaving that mindset? It's weird how people believe they can't be helped.
Of course they can be helped, but that requires an intense amount of 1-on-1 effort for a return that it quite low on the grand scale of things. And in many cases, it likely won't work. There are various ways to stem the tide that are far more useful, notably legislation against actions based in those philosophies and turning a general blind eye to Nazism as just another opinion. Unfortunately, given the current government, we are essentially moving in the other direction, with Nazism being given more cover and lateral movement.
If you wish to rehabilitate a Nazi, by all means. There is a probably a Nazi chapter within your current state as we speak, and I urge you to put forth the effort with great speed to stop the spread of Nazism. That offers something useful to the situation.
The others in the thread believe that one of the ways you stop the spread of something like Nazism is removing the ideas of support and safety. For example, were you a free speech absolutist, you'd think that removing Nazis from a forum would be a problem, but as a recent research paper noted,
de-platforming on Reddit actually lowered hateful commentary as a whole, because then new elements can not engage.
For a long time, we were kept from the wide spread of these ideologies because they were held by the opposing forces in World War II, who took them to their logical conclusion. Given a full illustration of what the philosophy unchecked leads to, America as a whole pretty much shut them down. (And I assure you, some punches were probably thrown.) It's only recently, given some the lax policing of certain internet communities - something that's beginning to change - that these groups
have risen in power and visibility. We've removed the stigma of Nazism, something that continues when you minimize it as just another viewpoint.
There are groups like Life After Hate and ExitUSA that handle Nazis in the manner some would like. I applaud their work, especially the work of former neo-Nazis to help their brethren rehabilitate. There are many various ways to tackle a problem. Theirs is a good one. It is not the only one.
De-platforming removes support, while others believe the threat of punching removes safety. The latter has been borne out in certain situations, as Nazi groups have cancelled rallies and whatnot. Essentially, in both cases, you're removing rights and privileges to show that a certain philosophy has no place in common society. I understand disliking that other method, but one cannot dismiss that it has in some cases worked to stem the issue within the vector that those folks care about. (There's a whole idea of "Violence is never the answer", but that's a whole other discussion.)
At the same time, I'm not particularly worried about an open Nazi being punched. Again, that's a local legal matter and it'll be handled as such. I don't worry about that anymore than one man punching another because he said something to his family member or spouse. I wouldn't, but I can understand why it happened and what the punch was meant to convey.