Marshmud: i have played many brain tournaments and won some, that works automatically, and the brains come from what the participants paid, so there is no magic increase or brain generation.

there is however a bug that allows you to create brains for you, basically without limit. some people use the bug, and make themselves tens of thousands.
Fencer didn't fix the bug, but instead declines if you buy memberships from illegally gotten brains.