I ran this race 3x in the early 90's when it first came out.
There is a couple of reasons big runners or even decent runners from our country do not go:
First, the beautiful brochure does not tell you that although the race starts at 6 AM, the last shuttle , the LAST shuttle is at 3:50 AM. Second, there is NO prize money. Third, it is REALLY expensive to go there. They make you get out of the park before 12 noon so the park is ready for the paying customers.
Fourth, the course is not as "scenic" as you might think. It goes through many back roads behind the scenes, and....it's 6 AM!!! Guess when the sun comes up on the east coast in Janurary? Around 6:45 AM, maybe. You run in total darkness, and for a long, long time total silence.
Fifth, and last, there are "restrictions" for spectators locations. Spectators arehere and there, and they can see you two times and at the finish. Period. There are no choices of where you can stand. So, as a runner there are 4,5, maybe 6 miles of just running in total silence and sometimes total darkness.