Because the 10:1 ratio sounds too pat. I believe the gov't of the time was too embarrassed to admit any higher ratio. Also, I believe the 10:1 ratio counted only male warriors. The women and any children who could handle a rifle were probably involved also. Data pretty much indicates that Custer was overwhelmed so quickly he didn't know what was going on. He was either extremely over confident or stupid or both........
You seem to know a lot about this. What exactly happened? Did Custer just ride into their camp shooting?