If one were to be naughty and not complete an itinerary as ticketed (i.e. abandoning the last couple of flight sectors, simply because the intermediate point was the real destination and the fare to the ticketed final destination was actually lower than that to the intermediate point), what could the possible consequences be?

Could they claw back any Frequent Flyer points? What about charging the fare difference (between the fare paid to the fare for the higher intermediate point at which the trip was abandoned) to the credit card on which the ticket was issued? Anything else?