You'd think writing would be an easy task. Look at me now. I'm doing it right now, and it isn't that hard. The thing is, technical writing is very hard. To be able to clearly explain something is difficult, and not in a fun way. It's difficult in the way that makes you wonder what you're doing with your life. It requires an understanding of the product you're using, so think about it this way. If you think reading those technical manuals is hard, imagine what the technical manual writer has to read to figure out what to write about.
Luckily job security is high in this field. Unlike a profession like taxi driving, technical writing is not going away any time soon. Even with advances in AI, we still require a human to write these instructions out so that they are effective.