It may just be the difference between how many people a video is relevant to and how deeply it impacts them. Things like tech, history, physics, and DIY channels each have fewer people who connect with the content than something like how to decorate nails.
One explanation could be the amount of investment one has to make to fully appreciate, and thus get value from, these different topics. For example, appreciating a "just for laugh" video generally takes less effort and specific experience than appreciating a technical video. This is related I think to the Law of Triviality [1].
At the end of the day though, I think there's somewhat of an inverse relationship between how many people you can impact with a given message (or video) and how deeply you can impact them. To impact someone more deeply requires deeper insight and shared context gained through experience on the viewer's part to interpret and appreciate the video, which necessarily narrows the target audience.
The system that disproportionately incentivizes the less deep content is probably the fact that the incentives are built around numbers of views, which doesn't discriminate between deep versus cursory impact on the viewer. If overall value of a video were calculated as number of people impacted multiplied by the depth of the impact, there would be more incentives to create impactful videos. However, most incentives currently reward only the number of people impacted irrespective of the depth of impact, and so it's much easier to produce videos that impact a lot of people with little depth.
Of course, this trivializes how difficult it is to actually build a large audience, which is difficult to begin with. Personally, I think they all have their place. Sometimes I want something stimulating to watch, sometimes I want something brainless.
[1] https://en.wikipedia.org/wiki/Law_of_triviality