I lost money (luckly not too much) in the stock market on a position where I was right and I didn't know why. I decided to find out and I learned that the size

I lost money (luckly not too much) in the stock market on a position where I was right and I didn't know why. I decided to find out and I learned that the size of my trade was larger than the Kelly criterion. The Kelly criterion seems to not be well known - why I can't say other than there are a lot of groups that benefit from people being ignorant of it.