Mike makes $4 an hour which can't happen (due to minimum wage) unless it was sometime in the 80s. I believe the reason Mike didn't quit was because he knew that there would be creepy robots walking around and he wouldn't want to let them in, it was the exact same thing. Until the 4rth night. It seemed as phone guy was trapped in the office and eventually said his final words (oh no) before being stuffed into a suit (probably chica). IM ABOUT TO DROP A BIG THEORY HERE!!!!
I think Golden Freddy was created by the government in a lab with the power of influence to end all world conflict. But considering the science in the 80s might not be to smart they didn't think that could use his powers for evil. Maybe using them to influence a security guard to kill a bunch of little children. The phone guy found this out and tried to save the world, but was careless and used to much of his power. Ending in his death and rebirth as Chica. I created this theory through the night five phone call reversed, phone calls, and in game newspaper clippings.
Let me know what y'all think