What was the main purpose for the French and Indian war?

I would say that this war happened because Britain and French wants to take control of lands in the west of the Appalachian Mountains. The Britain want the land to hunt beavers for their furs, the furs at that time sells for lot of money

The war provided Great Britain enormous territorial gains in North America, but disputes over subsequent frontier policy and paying the war's expenses led to colonial discontent, and ultimately to the American Revolution.