Fighting against your own government isn’t like fighting against a foreign power. You have the advantage of asymmetric warfare, and also the advantage that the military will not follow orders to just “steamroll right in through” citizens. Egypt has F-16s, but that didn’t stop the government from getting overthrown when the military decided to stay neutral. Libya had advanced Soviet weaponry, but Gaddafi was overthrown and killed by rebel forces.
Unless you’re willing to level your own country (which for practical reasons even
tyrannical dictators are not), fighting armed citizens is nothing like fighting a foreign war. (Also, the track record for advanced nations losing wars in places like Afghanistan with vastly inferior weapons is significant). The Syrian civil war also started with a civil uprising, with armed civilian guerrillas fighting government security forces. Again, there were defections when soldiers refused to fire on citizens, and that led to establishment of the Free Syrian Army, comprised of defectors from Assad’s regime.
Here is how it played out when Bangladesh declared independence from Pakistan. The Pakistani military was armed with modern US made aircraft and weapons, launched Operation Searchlight, which killed at least 300,000 Bangladeshis. Civilians took control of arms depots and started shooting back. That precipitated Bangali units of Pakistan’s military to mutiny and start fighting for independence. Military assistance from India helped win the war, but that started many months later. Without being able to take control of those arms depots to begin with, Bangladesh never would have been able to start the war that led to independence. (The American Revolution, by the way, played out more or less the same way. Guerrilla attacks at first, seizing weapons and supplies, creating a more formal militia, and then getting assistance of a foreign power.)
It’s not some crazy NRA fantasy. We have numerous examples of despotic regimes with modern weapons and aircraft being overthrown in civilian uprisings. I come from a country that exists because of such events. The Second Amendment is there to preserve that option. Had Bangladeshis been armed like NRA wingnuts in 1970, hundreds of thousands of innocent people might have been alive today, hundreds of thousands of Bangladeshi women may not have gotten raped by the Pakistani military, etc.