Is the ego a colossal mistake? Most spiritual teachings say so. They consider the ego an enemy, an illusion, some weed that has to be torn out, or a side of you that is fundamentally wrong and needs to be conquered.
The Diamond Approach does not. The Diamond Approach maintains that the ego is a state of an arrested or halted development of a process towards being the personal essence. That process has come to a stop or has slowed down tremendously. The personal essence is that part of you that can function in the world from essence instead of from your ego.
This is how A.H Almaas describes this question of the status of the ego in his book about the personal essence, called The Pearl beyond Price.