To shirt tail earlier comments, a good friend bought an RV kit, got about a third of the way through the build, and decided to call it quits. He sold it to a person from South America.
Another friend, and tool sales person, has an RV sitting in his hangar. Been there for years. Collecting dust. Will it ever fly? Maybe, probably not.
I'll bet that these two examples are the rule, rather than the exception.
The more I talk with individuals, the situation today is everybody wants a kit airplane (fill in your favorite model), and they want it flying now. Very few want to put in the time and effort to do a "hands on" build.
As we all know, the task of building a kit plane is monumental. RV's are perhaps the easiest to complete. But that does not make them easy. And all of you know what I mean. It takes time, patience, money, a highly developed skill set, an understanding wife, plus some extra help along the way.
Thus the rise in builder assist programs at independent shops. It is my understanding that you can have $200,000 wrapped up in your airplane when going down this path. Just don't tell the wife.....
The main thrust of this thread was not to determine any one's odds of success, but rather to get a handle on total kits sold to date (June, 2020), and total completed airworthy kits to date. Of course, those numbers are dynamic and change daily. 50% seems like a pretty good guess.