For the same example, let's say 5 people bet for the winner, and only 2 for the loser.
The house pays out 5 winners, but only collects from 2 losers.
That's exactly why the lines are set to try and entice 50/50 bets on each side. Vegas doesn't care who wins or loses a game. They don't have favorites. They place the lines based on who the public bets on.
They usually are pretty close, but every now and then you'll hear about a rare upset in which the house gets completely smoked.