What is fame anyway? Does it mean a Youtuber with a channel that attracts a lot of nerdy people? A pop idol that teens talk about and lives in nostalgic memory of former teens? A writer whose works live on for decades? A Nobel winning scientist no one knows about until the day of the award? A soldier who is only remember for one heroic act before he died? There are just so many ways we can think of fame. By definition, a famous person is someone who is widely known, but the way they are known is what needs further clarification, especially when more people are trying to become Kim Kardashian and succeed.
I used to read about a theory that a lot of planets above the horizon can indicate fame, but I can see some famous historical people with almost all planets at the bottom of their charts. Some really famous people don't have any Leo/5H personal placements. Some, like Kurk Corbain, even have a high concentration in Pisces. So yeah, with no fixed definition of fame, the statistic is all over the place.
IMHO, fame is more of a "stroke of luck", and it has less to do with the natal chart itself, but more to do with the specific transit that trigger the "fame" moment. The natal chart may indicate someone's willingness to work for fame. And when they finally meet their lucky transit, the fame comes. It's pretty much a "preparation meets opportunity" thing.