Bikers and Nazi paraphernalia have a deeper connection than "it looks cool and pisses people off." The biker movement and aesthetic arose from WW2 veterans. They were traumatized by the war and often felt they had no place in society when they returned. Many joined biker gangs in an attempt to find common community with other vets. Many wore plundered Nazi gear as evidence of their service to society and protest against the shit they dealt with from other citizens.

For sure some were neo Nazis or shit stirrers.

At the same time, it's worth examining the narrative Satanists apply to the fallen angels. They see the rebellion of the angels as an act of revolution and bid for freedom against a tyrannical force. They don't believe in a literal god or Satan but that story has appeal when they see an ascendant Christianity in American politics enforcing Christian dogma on the rest of us.

I think there's more reason and purpose in both contexts than they are usually given credit.