It is about power. Once a person or group obtains power, they will fight with all that they can to retain that power. If conservatives come to power within the GOP, then the establishment republicans will have to give up power to the conservatives. Their agenda is less likely to be enacted, especially when that agenda is different than the conservative agenda.
Speaking of that, “The 48 Laws of Power” by Robert Greene would solve a lot of confusion Freepers seem to have about this stuff.