I heard someone got 300,000,000 simoleons of bill in one go. Actually it was from using ATM card mod.
Some simmers don't like to do money cheat but want to do a nice start with a decent house. So they want to get a big loan from ATM for buying a nice house. A week later, they get tons of bill and go broke.
Or in my case, the bill gets increased while collecting lots of gardening fruits and flowers, space rocks, my sims trophies, etc but it was not that much though. It was around 30,000 to 40,000.