I don't agree. This is suggested before and rejected if I'm not wrong. And why? Because it's a part of the game to make money with props, and it's not really that hard to make a lot of money. If you play the game well, maybe you have to buy props once in a month. Besides it's a part of the fun too to chase people with a lot of cash to buy props, this is something that would happen less if there would be more money in bank.
That's why I say -1. If you want more money in bank, make a donation and you're able to store 12 mil.