Traditional gun enthusiasts have "their scenario". That is, the thing they think they will need their cache of ARs and survival gear and 10k rounds. SHTF, end of the world as we know it, meth addled home intruder, zombie apocalypse, whatever.
I think folks on the left never had "their scenario" and correctly assessed the odds of those scenarios happening was low. So, logically, no need to arm themselves.
Those odds have changed and we've been watching those scenarios play out live on social media. Leftists have taken notice and are adjusting their relationship with firearms appropriately.