The most fascinating thing is they do not know why they do it. Some younger ones just do it for a laugh or publicity and the results are usually very obviously hoaxed. No, and it is hard for me to imagine anyone wasting precious time and energy on such a feat as hoaxing a circle. We understand that there are records of crop circles from as early as the 16th century. There are three records of crop circles in the 1600's, but the modern-day phenomena started around 1923 with small numbers up until 1976, at which point they increased in number and complexity.
Crop circles seem to be evolving into increasingly complicated shapes.
They also seem to have evolved through a series of strikingly different themes over the years. In general terms, we appear to have been spoon fed images of animals, insects, mathematical models, fractal geometry, and, in recent years, astronomy. If they had remained just circles, by now they would be just accepted without question as part of our humdrum reality. Perhaps someone is trying to hold our interest or attention. Remember, our attention spans are growing shorter and shorter these days.