Time was against the Indians, as it usually is with aboriginal civilizations. Whether it be the military, civilization's advancement, the railroads, the slaughter of the buffalo, the Indian lifestyle was DOA. They just didn't know it, nor could they.
Unfortunately, while many in the military dealt with the Indians in a relatively humanitarian way (for the period, and after subjugation), the government in all its wisdom saw differently. Money was to be had and the Dept. of the Interior did everything possible to see that the proper parties were compensated while the Indians were left to shift. A sad tale.
Ironies abound. Custer didn't hate the Indians and they didn't hate him. He opposed the policy of forcible return to the reservations, testified against it in front of Congress, and nearly lost his command as a result. Major media darling. May have been the most photographed man of the 19th century. Had he lived he may have been the tribes' best hope at stopping the policy that led to the battle.
He does appear to have lost track of precisely where their forces were on his approach. Reno's movements were probably responsible for that. I would not categorize Reno's performance as a "betrayal" although he was court-martialed and several contemporary analysts did so. But certainly he also wasn't where Custer expected him to be.
The hill itself is a lousy defensive position but was probably the best one within reach by the time Custer did figure out what was really happening. But he'd have been flanked at some point unless he were relieved - the Lakota and Cheyenne had some of the best light cavalry commanders in the world at the time. Preventing that was probably why Keogh was where he was. That isn't obvious on a map but standing there it's pretty clear.
That's just my subjective and admittedly amateur impression. BTT for a great topic.