according to the men at the camp, why did some men still choose to fast on Yom Kippur? Why did weisel decide not to fast?

Some men fasted because they still believed in their faith. Perhaps this ordeal might be a test God was putting them through or what was happening was God's will (in some twisted way). Eli didn’t fast because, “there was no longer any reason for me to fast. I no longer accepted God’s silence” This was Eli's small act of rebellion against a God who had let him down.