Edit: my post below is not true. The overall distribution is indeed close to Gaussian; see here: https://news.ycombinator.com/item?id=31861089
*******
The CLT simply says that the distribution of a sum of random variables will be Gaussian (as the number of random variables being summed tends to infinity).
It is not obvious to me that the agent-level difference equations in this simulation would naturally lead to the overall distribution of wealth being a sum of random variables.