The founding fathers have written at length on their reasoning for including the right to bear arms in the constitution. It is very clear that they believed in the people’s ability to resist and overthrow the government if needed.

After all, this was a group who escaped the grip of the monarchy through force of arms. It’s odd to think that they didn’t see value in the ability of the people to do the same, especially when they repeatedly wrote about it in period.

However, all that being said, I agree with your sentiment that leftists should be arming themselves. Just because the 2nd amendment has almost completely lost it's original intent or meaning, doesn't mean we can't take advantage of the fact that it exists with tons of legal precedent to strap up in preparation for what might come next. Things are unlikely to get better from here, and if things get worse you will be glad you have a firearm for protection.

Also this here is kind of the point. The original intent is not important; many people believe in the modern era that an armed citizenry is important as a last ditch balancing force to government overreach. We are all better off if left leaning people arm themselves instead of using pro-gun arguments as some sort of self-righteous gotcha against the right.