Quidditch

There's a big ball called a "Quaffle", which, when thrown through a hoop, is worth 10 points.
But the game doesn't end until the "Golden Snitch" is caught, which happens to be worth 150 points.
Then, what's the point of catching the Quaffle? Shouldn't everyone be trying to catch the Snitch? Would you stop chasing the snitch if your team's up by 160 points? How often does that happen? But the losing team would stop chasing it also, in order to prolong the game.
This is what happens when a woman who never played sports as a child has to come up with a game.