Okay, then he obviously overestimated his own prowess.
Something didn’t work out too well.
Hello Sherman, Did you know that of 647 men with Custer, only 210 fought during the whole battle? 400 men, with Captain Benteen and Major Reno were detached for a front attack and scouting. William Taylor, private and survivor of the battle, wrote this: "Reno proved incompetent and Benteen showed his indifference – I will not use the uglier words that have often been in my mind. Both failed Custer and he had to fight it alone." (William Taylor, 02/20/1910) US general in chief Nelson A. Miles wrote in his autobiography in 1898 that Custer had been betrayed by both Benteen and Reno. The man responsible for the Reno Court of Inquiry, the only federal inquiry of the battle, agreed with Miles. See http://www.custerwest.org for the whole case
I’ve read a number of stories about why Custer’s attack failed.
One was due to archeological evidence showing that many troopers’ carbines were affected by continual jamming.
This led to a slower rate of fire and the Indians took advantage of this by moving in closer than they were earlier in the battle.
The decline in overall rate of fire apparently also rattled many of the troopers which could be noted by how separated they became from one another along Battle Ridge Hill.
This, of course, is only one possible scenario.