Some interesting perspectives posted on what it takes to build a string of 4* horses and sponsors. Thanks so much for the link to the wsj article!
I suspect there are also other factors in building a stable of owners, as well as horses, who will back a pro rider up through the 4* level. I have wondered if learning the practical skills needed to handle such a program at an early point in one’s career doesn’t make a big difference.
Buck has a lot of support for UL horses - he grew up in one of the barns that created the system.
Phillip has a model of the system. Boyd learned from Phillip. Ryan learned from Boyd. Ryan comes to his first 4* with three horses. Boyd comes with three horses almost every time.
As has been pointed out, several ladies have benefited from the mentorship of KOC. But I wonder if the women generally are less plugged into the mentorship network?
Also: U.S. top-tier riders have said a lot about how hard it is to both market themselves and keep their programs going at the same time. They have a lot of away time doing clinics, which are essential for both income and making contacts. (Some 4* owners/sponsors started as students.) That means that they have to be able to manage a system back at home that keeps the horses ridden, and ridden well. And, managed properly by people who know what to do about all the little things that happen. That’s not something a pro knows how to do intuitively - they have to learn it from someone else, or from hard experience.
And - I wonder if women eventing pros don’t also frequently adopt a different model for their careers. I can think of a number of female eventers, who have ridden at 4*, who have a fairly large loyal, even loving, following, students and families who offer them a solid base and a good income, who lesson, event, buy horses, board, etc. BUT - it is all about the student, not so much the pro.
These students pay the female pro to ride their horse - and then return said horse to the student to ride. The pro is always making up horses for other people, not for themselves.
Being a 4* owner means paying for someone else to ride at the highest levels. I think that at this point in time, many more loyal followers pay women pros to ride horses for the student, not the pro.
Do these female pros actually want a different business model that would give them a 4* string? If they are making a reliable living working for their students, it may be hard to step out into the realm of sponsors who pay them to ride for themselves. Of course a syndicate helps, but if a sponsor walks away, there may be less of a fallback than losing one student out of many.
Just some observations. 
I would really like to see a study of how the 4* strings are built and maintained, and what is in common between the pros with those strings. I think that would be useful for younger riders dreaming of riding at the top.
