Him revealing that he's had depression since mid-2014.
By its very nature, a lot of the personal life stories he shares in his We're Still Here videos, as well as the similar experiences shared by viewers in the comments sections.
The death of one of his cats, Spaghetti. Especially bitter is that, prior to this, the community had come together to raise money to pay for his surgery for an internal issue. The surgery worked, and Spaghetti was cured. Until months later, the problem came back worse, and LK and his wife had no choice but to put him down.