I would say you are underestimating North Korea's capabilities. The loss of life regardless of who "wins" in the end would be horrific.
While the nuclear and missile programs get all the attention, a seriously underappreciated threat comes from North Korea’s arsenal of conventional weapons, including the world’s largest artillery force. A third danger comes from the country’s elite special operations forces that could magnify the impact of a North Korean strike on South Korea.
South Korea’s capital city, Seoul, is a so-called “megacity” with a whopping 25.6 million residents living in the greater metropolitan area. It also happens to be within direct firing range of thousands of pieces of North Korean artillery already lined up along the border, also known as the demilitarized zone. Around 70 percent of North Korea’s ground forces are within 90 miles of the DMZ, presumably ready to move south at a moment’s notice.
Simulations of a large-scale artillery fight between the North and South produce pretty bleak results. One war game convened by the Atlantic back in 2005 predicted that a North Korean attack would kill 100,000 people in Seoul in the first few days alone. Others put the estimate even higher. A war game mentioned by the National Interest predicted Seoul could “be hit by over half-a-million shells in under an hour.” Those results don’t bode well for one of Washington’s closest allies, or for the tens of millions of people living in Seoul.
And that’s not all. A report from Stratfor, a private intelligence analysis firm, found that a large-scale North Korean artillery attack would likely mean that the northern half of Seoul would get hit the most. Depending on where North Korea placed some of its rocket launchers, southern portions of Seoul — including the Gangnam District of “Gangnam Style” fame — would also be within range.
The Stratfor report further notes than just “a single volley” of North Korean artillery could deliver “over 350 metric tons of explosives” into greater Seoul, “roughly the same amount of ordnance dropped by 11 B-52 bombers.”
As if that were not enough, North Korea has a robust chemical weapons program. South Korea’s Ministry of Defense estimates that its northern neighbor has between 2,500 and 5,000 metric tons of chemical weapons, including sarin and VX nerve agents. (Sarin is thought to be the chemical agent used in the Assad’s regime’s recent attack in Syria, which killed 72 people and left children gasping for breath as they choked on the poisonous gas.)
Should North Korea attack, it might use chemical weapons early on in South Korea’s urban areas to increase the death toll. At the same time, conventional munitions could rain down on the South. After that barrage, North Korea’s 200,000-strong special operations forces should have an easier time arriving via tunnels, mini-submarines, or Russian biplanes. Surely Pyongyang would find a way to employ its growing cyber capabilities, too, because why not?
Granted, North Korea is not expected to win a full-blown war with South Korea, should that come to pass. For one, America has the ability to stop a North Korean missile launch before it even happens with cyber capabilities.
But even if a launch did take place, the THAAD system being deployed in South Korea should be able to take it down. If that missed, Aegis ships in the Pacific could shoot the missile; and if that failed, Patriot batteries could also stop the flight. And if all that failed … well, you know. The bottom line is that there are lot of defenses in place designed to stop North Korean missiles, but nothing is perfect.
North Korea has far more troops than South Korea (1.19 million versus 655,000), but should a conventional fight break out, US and South Korean air power would help balance the scales. But, again, nothing is guaranteed.
Either way, North Korea could cause a lot of damage and harm a lot of countries — and people — as it goes down.
This is only part of the article but I suggest you read the whole thing.