Prepare how? Stock up on range toys and ammo, like some people on here are saying?
That's not going to be nearly enough - they wrote 2A based on the assumption that there will always be more than enough white supremacist goons to overwhelm any leftist resistance - and, so far, that assumption has proved perfectly correct. The people at Blair Mountain was armed to the teeth - so were the people in Greenwood. US-style "gun culture" has never served the left very well - I'd argue that it actually does something even worse than nothing... it lulls leftists into a sense of false security.
I'm not saying arming yourself is a bad thing... but the idea that firearms mean automatic salvation is a peculiarly US-only idea that has more to do with pop culture than reality.
The left has been playing nothing but defense since the Culture War began, and it just took four years of Biden's liberal counter-insurgency to sweep even that under the rug. That's where the weakness of the left truly lies.