The important argument I took from Angela Nagle’s Kill All Normies is that the ‘alt-right’ reflect transgression detaching from progressivism. The idea that an act that goes against a law, rule, or code of conduct is inherently progressive ceases to be tenable when progressive movements have institutionalised laws, rules and codes that serve progressive ends. Under these circumstances, transgressing against ‘political correctness’ or ‘cultural marxism’ can easily cast itself as authentic rebellion against received wisdom, with all this entails for its capacity to recruit.
There’s a passage in the forward to Daniel Bell’s The Cultural Contradictions of Capitalism which sheds light on how we got here. From xxvii:
The paradox is that “heterodoxy” itself has become conformist in liberal circles, and exercises that conformity under the banner of an antinomian flag. It is a prescription, in its confusions, for the dissolution of a shared moral order.
But that confused prescription was the progenitor of a new orthodoxy, something which Bell cautions is never “the guardian of an existent order, but is itself a judgement on the adequacy and moral character of beliefs”. The social victories of progressivism institutionalised a confusion about its character, perpetually valorising transgression even when the old orthodoxy it transgressed against had long since eroded. This is the aporia which the alt-right have (organically) exploited and perhaps why this strand of nascent right-populism has proved so baffling to orthodox liberals and leftists alike.