We are certainly all-in when we can see Jesus working miracles in our lives. But our faith gets shaken when we cannot see His works and start doubting even the existence of God. If our faith is based on the works of God in our lives then we will not go far with Him but like a drug addict keep coming back to Him only when we run out of money/blessings. Peter was still immature and did not understand what his response should be when Jesus foretold his denial.
The chief priests and the elders were assembling in the palace of the high priest, Caiaphas, and were trying to figure out the best way to dispose of Jesus. They were looking for a way to secretly kill Jesus without riling up His followers. When they were perplexed and could not find a way to dispose of with the Jesus problem, satan presented them with an opportunity that they quickly grabbed on to.