Re: Game is ruined by these cheaters abusing the money exploit.
There is no way to code something that can't be hex edited. Even if all the code is on the server side and only a client that recieves basic input from the user on the client side it can still be hacked to do things outside the scope of game design. I've seen hacks for MMOs that have all code on server side that allowed players to teleport at any time and many times repeatedly in seconds to only be seen for a split second as they appear to perform a task then disappear again. Somehow despite all the code being server side they still hacked the game to do something outside the design of the game. This historically has been established as cheating. It doesn't matter how you manipulate the game outside of the game to make the game do something it is not designed to do.
On the otherhand there is exploiting which is by definition something different. Exploiting is doing something the game was designed to do in a way we were not intended to do it. In my typical experience as it related to online (MMOs etc) that have a game economy get rich quick "methods" typically are considered exploits and the developers will patch and then punish everyone who took advantage of the exploit. The punishment typically ranges from a permanent ban to removal of all goods gained from the exploit. However given the length of time this has been known to be a possible exploit nothing has come of it to patch it. Which leaves the question of do they concider it an exploit. My guess would be no because you would artificially speed up your leveling process there by making it significantly harder to actual develop your city after you amass a rediculous amount of simoleons you could get as you play at the designed pace of the game instead of all of it before you start. By that I mean I think it would take you longer to get to your goal of X population by doing that vs simply playing the game as intended.