Why did ancient men say "from the palace" after castration?

Speaking of an ancient occupation, I believe everyone must know that it is the eunuch in the palace. What does eunuch mean? It means that a man who has cut off his reproductive organs and has no viability enters the palace to work for the emperor and the harem concubines, and is called a eunuch.

? There is a special institution in the palace to help those who want to enter the palace to remove their reproductive organs. Moreover, in ancient China, men who were able to enter the palace had to undergo strict inspection. Except eunuchs and emperors, it was very difficult to enter the harem.

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? From here, we can also see the particularity of the eunuch profession. Then, since others have cut off his reproductive organs, why did people call this thing "self-palace" in ancient times and now? Why use such a word? It's like castrating yourself and cutting it off yourself.

The first reason is that choosing to be a eunuch in the palace is a decision made by some people with very difficult lives, but it is their own decision, so they agree to castrate themselves to some extent.

The second reason is that the rules in ancient China were very strict. These people who are willing to be castrated must register first. Only after approval, do you have the right to choose a very good day for castration. And this good day was decided by themselves and the officials at that time. So, to some extent, they decide their future life.

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? The last reason is that many people were forced by life in the late Ming Dynasty and had no extra money to bribe organizations that recruited eunuchs. So many people castrate themselves, which is why people always use the word palace instead.