Look at it this way folks. You started with nothing, and eventually you won 100 credits in a game. You can go spend that 100 credits on balls to leave you with nothing, but the earnings will always show that you have won 100 credits in monetary value.
Repeat the above, as you win 100 credits again, and again spend it to leave you with nothing. This time the earnings will show you as having won a total of 200 credits in monetary value. As you go on winning credits, the earnings will go up and up. But it is only there to show how well you are doing at winning credits, thats all.