Bhante Sujato. Meditation on purification of the mind and doing as few things as possible. Dhamma talk on part two of the Buddha's life covering the Buddha's practices before his enlightenment, focusing on self-mortifications and MN19 Two Kinds of Thought and MN128 Corruptions. References: Earliest example of sunk cost fallacy: DN23#29.1 Pāyāsisutta