[rmc]

Remember that the bitcoin network adjusts itself to try to only have about 25 bitcoin per 10 minutes mined. So if you were to jump into the pool with loads of cpu power you'd get a few bitcoin for a whole, then it'd adjust to be harder, raise the bar, and you're back with the same generation rate

[IanCal]

Yes, but you'd be getting more of the pie. The pie remains the same size, granted, but you can still make quite a lot from owning a significant portion of the processing power.