Custer ignored the opinions of his scouts as they were approaching the area. The scouts looked at the tracks and sign on the ground, and told Custer that columns of Indians and horses were converging. Custer disagreed, and asserted the trails were diverging.
His scouts consistently put the numbers of Indians ahead of them at “at least 2500,” and Custer kept downplaying this number to less than 2000. The eventual truth came in at far more than 2500.
From all the accounts I can find to read, Indian and white/USA, Custer simply comes off as a cocksure, brash commander who could not respect the opinions of subordinates. His early success as a battlefield commander, in retrospect, had a large element of luck.
Luck eventually runs out, and when there isn’t cool competence to back it up, the truth comes to the fore.
Custer and Obama have/had the commonality of self confidence in themselves.