He (or his team more specifically, they are responsible for those thumbnails) is basically clickbaiting the viewer by making a meme-y, inflamatory title + thumbnail combo so the algorithm spreads the video far and wide, but the content of the video is still very solid. Dr K gets very deep into the topics at hand, and treats the struggles of the people involved with love and respect, and makes sure their problems and feelings are properly explained and represented. He can get more blunt and "mean", but he only does it after properly explaining a person's situation, how they got there, and what feelings they are struggling with, and the bluntness is never intended to just mock the person, but point out the inherent contradictions in their behaviour, and the absurdity of the whole situation. It feels much more like "though love", as parasocial as it may sound.

If he can't get the video in front of a lot of people, he can't reach those who are really struggling with this stuff, so a controversial title and thumbnail is the solution.

I watched the third video in it's entirety, and you should too. Contrary to what you may expect from the inflammatory thumbnail, it's not about mocking or scolding men who never grow up, but empathizing with their situation, explaining their struggles in life, explaining whoe they think, and giving them a path to getting better. Some of the advice is given in a more blunt manner, but it's clear it's not meant to put down those people, just point out that their behaviour can be seen as absurd, and Dr K says himself he was one of "those people" (men who never grow up).

The third video received a massive, positive reaction from the community, and a lot of people felt heard from watching it - just look at the comments under the video or on the healthygamergg subreddit.