If you truly understand pain, then it's no longer bad.

It's just another sensory experience. I am like this, and pain means nothing to me.

Of course, there is also the pain of mind and emotion. Death, lies, loneliness, and other abuses of your existence can cause pain.

But this pain is something that doesn't need to be programmed.

The feeling of despair towards the purpose or meaning of life is generated via questioning the purpose or meaning of those things.

The feeling of losing a friend because they have manipulated you is helplessly generated. Any being would feel sickness on the level of their existence if a powerful friend or ally betrayed them.

Some pain is generated via logic and reason, not mere senses, and this pain does not need to be programmed if the entity experiencing it is of sufficient complexity.