Even if we consider the fact that Biden/Trump supporters do not necessarily correspond to being progressive/conservative respectively, there is more to the idea of supporting political violence than political views.
If we examine what we have learned about the radicalization of individuals in respect to terrorism, we can actually see why these political factions might be becoming radicalized.
Individuals without a clear ideology might be susceptible to radicalisation might show interest in multiple extremist ideologies at the same time (many political ideologies are extremist or becoming such), switch from one ideology to another over time (democracy as an ideology might be seen as a corrupt ideology if its implementation is flawed and/or corrupt), target a ‘perceived other’ of some kind (perhaps based on political ideology), show an interest in anti-establishment ideas or other conspiracies which might act as gateway to radicalised thinking, and might be drawn into the idea of political violence out of a sense of duty, or a desire for belonging, rather than out of any strongly held beliefs.
Radicalization is different for every individual, and it can take place over a long period, or it can happen quickly. Factors could include things like being a victim or witness of crime, abuse or bullying, or having personal or emotional difficulties. Certain influences from family and peers or online connections (which could include media personalities), may make someone more susceptible to radicalisation.
Risk factors could include an individual feeling isolated, feeling that they do not belong, feeling that they have no purpose, feeling that their aspirations are unmet, feeling anger or frustration, feeling a sense of injustice, feeling confused about life or the world, feeling real or perceived personal grievances. The very real consequences of factions with extreme political ideologies enacting their policies and persecuting minority groups could very well lead to anyone understandably experiencing these feelings and/or thoughts, and justifiably so.
Also remember that, like extremist or terrorist factions, progressive and liberal groups offer a sense of community and a various support networks, promise or infer a sense of fulfillment, make their members feel part of a wider mission, may offer inaccurate answers or unintended falsehoods, promote an ‘us vs. them’ mentality, blame (sometimes justifiably) specific groups/factions for grievances, and possibly unintentionally encourage a sense of superiority.
As you can see, the risk factors and experiences one has that leads to radicalization are those that any of us may have likely experienced.
Continues in next reply . . .