Custerology: far more than the study of "Custer"
It also might explain the German fascination with Indians in general and Karl May's Winnetou in particular. And the American love of mascots and other stereotypical Indians. Note that all these people focus on the Plains Indians and the associated stereotypes: chiefs, braves, teepees, etc.
Elliot gives us a plausible explanation for this. It's one I've expressed many times also. Namely, that in celebrating Plains Indians, we also celebrate our victories over them. They were savage and fierce, wild and free, which we consider good qualities in warfare. And yet we defeated them, which proves we're even more mighty militarily.
This also explains why we build monuments to half-naked savages and not to civilized Indians such as Sequoyah, Charles Eastman, or Vine Deloria Jr. Honoring Indians for their modern achievements doesn't bolster our fragile egos. It doesn't reinforce the message that ultimately we're no. 1.
So we focus on their "primitive" achievements because they're irrelevant to us. Who cares if Indians were brave and noble? So were the ancient Greeks and Romans, but we don't make decisions based on them.
What's past is past, and the Indians eventually lost. We "honor" them like we honor American Idol losers, who also don't matter. Then we break their treaties and take their land.
If we acknowledge that Indians had viable cultures and civilizations, it would call into doubt our dubious behavior. We destroyed these cultures and civilizations because we thought ours were better. That's still our operating principle: that Western (i.e., white Christian) civilization is the pinnacle of creation.
Our entire society is built on the assumption that our values are incontrovertible. Because we think we can do no wrong, we invade other countries, heat up the climate, fill the ocean with garbage, consume vast quantities of resources, etc. Once you start questioning these values, the whole house of cards threatens to fall down.
For more on the subject, see America's Cultural Mindset.