I think you've got it a little backwards. All lore points to Pahanin making SGA after becoming paranoid from the events in the vault. Likely, he always had some fear issues and talked to himself as a means of coping. But the events of the vault traumatized him and forced him to build something that talked back so he would never be alone.
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Oh, it's pretty clear Pahanin had some issues with fear, since the quotes we get from him all seem to indicate a degree of paranoia. Such as his one from a Warlock Gauntlet - "I can never shake hands with Warlocks. I always get so afraid they're going to vaporize me."-Pahanin Errata.
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Actually he made it so something or someone knows he exists.
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As a counter to the Oracles ability to erase things that exist.