The Amendment process is rather arduous, which is why the gun control crowd have never really tried to use it.
As far as firearms being inadequate to counter forces that have aircraft, artillery, even nukes, there are a few things you might consider, Alx:
1) You assume that government forces would be willing to use such weaponry against the citizenry they are supposed to protect, and to an extent that exceeds the casualties the citizens would be willing to accept;
2) This assumption hasn't played out so smoothly in various venues, such as Libya or Syria, where the opposition shouldn't have had (or currently have) a chance, but they are willing to accept pretty heavy casualties, or in places like Afghanistan or Gaza, where US and Israeli forces, respectively, accept constraints on use of force and restraints on infliction of collateral damage;
3) You also assume that the Executive, Legislative, and Judicial branches would be willing to run the risk of ordering or approving such use of force.
The fact that government actually has to consider the possibility as more than an afterthought is one of the greatest values the Second Amendment provides.
Besides, while fast reloading firearms do allow a lone wolf to potentially inflict disproportionate damage, they also allow lone individuals or small groups to have some chance of fending off mobs. Mobs don't need firearms to inflict massive casualties - just ask the 2,000 Muslims killed by mobs in Gujarat, India (via blade, bludgeon, and arson), or the 800,000 Tutsis killed by Hutus in Rwanda (mostly by machete, some by club) if they wish they had been armed with modern firearms.
What's that, you say? The government will protect you from that sort of thing? You mean like the UN peacekeepers protected the unarmed Muslims at Srebrenica, when the Serbs came calling, and the blue helmets decided discretion was the better part of valor? 6,838 IDENTIFIED victims, plus a few thousand others, might disagree with you rather strongly.
But you say that kind of thing could never happen in the US of A? Of course it couldn't.
Nothing like that happened at Wounded Knee... or Waco... or Rosewood (actually, Rosewood was the only one of those examples not carried out by government forces).
But keep supporting the rose-colored glasses crowd; obviously such things could never, ever, ever happen again....