I don't want to live on this planet anymore.
Some nerding:
From a technical perspective that's less an issue with people and more an issue with the technology design. People aim for the most comfortable, ergonomic way to hold a smartphone. Which is, you already know it, holding it "vertically" (= long side up, small side sideways). You can easily do it with one hand, whereas you usually need two hands to hold it horizontally. However, it is easily possible to place the camera sensor chip such that it can capture images in widescreen format even when holding the device vertically. Manufacturers usually don't do this, because they want to allow a more intuitive handling, like "what you see is what you get". If you hold the phone horizontally, this is directly reflected by a widescreen image and the other way around.
Since people also usually hold their phones vertically when using apps, several platforms, like YouTube for example as well as their content creators, have developed improved support for this. So you can continue mindless scrolling while enjoying more of an image. If the videos / images were in widescreen, the image would be scaled down and details might be missed when holding the device vertically. You would have a lot of black and just a small box in the middle with the images or videos. Probably everyone who reeds this will have experienced this.
However, this is of course annoying for people who don't mind holding the phone vertically or who are watching videos on a widescreen device like a PC monitor. And that's not a surprise. We humans evolved to have a larger field of view in horizontal than in vertical direction. We can see more to our sides, but less in up-down directions.
I don't fear that movies or shows will be recorded in this format (other than for artistic purposes), since that's a thing where even the comfortable "vertical phone holders" will prefer the wider screen format. But for cheap low effort content or shorter videos and if the target platforms are usually used on smartphones, this is probably a nuisance we have to learn to live with. ;)