When you live in a society where the social-media lynch mob can cause you to lose your job for publicly stating things like "I'm against any further immigration" (note: not my view, it's just an example), etc, then the only place to voice these views becomes these radical parties.  A liberal society that allows no dissent from the prevailing narrative, that does not consider the merit of views aside from the current canon, I think is actually the cause of the coming rise of the far-right.