If I have 2x as much hashpower as I did yesterday, i'll get roughly 2x as much bitcoin as a reward (which over time will go down as the global hashrate goes up).
In other words I'll get a larger percentage of global bitcoin production, which is fixed.
One of the largest US mining operations are said to be located in Seattle where there is dirt cheap hydroelectric. So are many of the Chinese operations.
It's not as mich of a zero sum game as it might seem, it's more of a race to the bottom.
If your competitors are running on cheaper electric, you'd better find some cheaper electric or they are going to increase the difficulty to the point that it's not profitable for you.