Initial xcom "starting money" is around
https://www.ufopaedia.org/index.php?title=Country_Funding_%28EU%29Base funding values from data are: 600, 230, 240, 320, 250, 160, 140, 245, 400, 150, 300, 280, 180, 310, 160, 110;
Summ of them is 4075. But game uses value+random(value), thus is avarage it will be value*1.5.
But actually it's value from 4075 to 8150 thousands.
Plus it runs through base maintain precedure, which cuts first values BEFORE game starts.
I guess that initial maintaince precedure is skipped. It will be fixed, but it's the thing of low priority.