For Kim Jong Un negotiating with the US is a waste of time
When it comes to the denuclearization of the Korean penninsula, the US is desperate to get anything accomplished that could possibly lead to denuclearization. However, North Korea's nuclear weapons gives the North the upper hand over the US in negotiations and North Korea will likely continue developing and maintaining nuclear weapons until the US can somehow convince them otherwise. North Korea's strong bargaining position makes holding negotiations with the US a waste of time for Kim Jong Un, which explains why Kim Jong Un decided to visit a potato farm instead of meeting with US Secretary of State Mike Pompeo.
From the perspective of Kim Jong Un denuclearization is not at all beneficial. Denucleariztion really just leads to North Korea losing a major bargaining chip. The only way denuclearization could possibly benefit North Korea is if the US actually removes all of their military presence from South Korea. But Kim Jong Un would have to be very naive to believe the US' claim that they would completely remove their military from South Korea.
The US on the other hand has strong reason to care about the denuclearization of the Korean peninsula. For the US a denuclearized Korean peninsula would lead to more safety for their ally, South Korea, which could possibly lead to spending less money on South Korea's national security. The US would also no longer need to worry about the security of other Asian allies, not to mention the security of the US itself.
Featured Image Source: RT