I could give you many reasons; there are many blogs and articles about why you should write a book in your industry.
There are two reasons. The first is that sharing our knowledge and passion is natural as coaches or teachers. If you don't like to give, you should not teach. The second reason is more prominent. Creating databases on the different figure skating jump techniques creates a significant problem, especially when made on an Excel Spreadsheet. Imagine displaying 50-60 columns of other data, then adding 50-100 rows of skaters. It's going to be big quickly. To solve this, I created the front page for each jump called the ID card. But it's still easy to digest. Here comes writing more and explaining the complex moves, details, and observations. This was the starting point of the "Figure Skating Jumps" ebook.