Park Geun-hye in her presidental term had repeatedly stressed that the Korean reunification will be a bonanza ("통일은 대박이다"), but this unusual and ultimately information-free slogan turned out to be coined by Choi Soon-sil, a cult leader behind Park Geun-hye. Choi wanted to, literally, make NK collapse in two years after the sudden closure of the Kaesong Industrial Region in 2016 in order to pave a way to Park's reelection---while the current Constitution of South Korea does not allow for the presidental reelection, critical events like the collapse of NK can force amendments or even allow excuse to the Constitution. Choi even tried to leverage those future events into huge returns by buying land near the 38th parallel.
After Park's impeachment, it was revealed that there were multiple attempts from NK (yes, you read right) during the Park's term to make contact to SK, only to be ignored. For example, top officials from NK visited SK during the 2014 Asian Games in Incheon and (unsuccessfully) asked to arrange a meeting with Park. This breakdown was for a long time attributed to NK, but in reality Park (and in turn, Choi) had just ignored the request.
[1] The primary source is an interview of Jang Shiho from Lee Gyu-yeon's Spotlight (a JTBC programme), but individual points were also independently confirmed via multiple sources. Jang was a niece of Choi Soon-sil and eventually sentenced to 2 1/2 year imprisonment in 2017 after giving much clues to investigators (for plea bargaining).