Additional Finance

Good day guys, why does the price of your additional Finance keep increasing as your coins increase? I have got to 2119 before on the game and it got to a stage I stopped purchasing additional Finance as I was very influential and winning titles on end. But anytime I have need to purchase, I go to see more than 100% increase in the price of additional finance especially the billionaire investment. I have been wondering why the price of investment has to increase. Any reason(s) why?