Skiplagging. How is it ever cheaper to go from point A-B-C than it would be to go A-B?

Question

I understand that skiplagging is finding a flight that is cheaper to go from point A, to B, with a planned trip to C, but just leaving the airport at B.

I don’t understand the basic concept of how this happens though. How is a flight from A-B-C, ever cheaper than a flight just A-B? The extra cost of the C leg would have to be entirely absorbed by the savings from A-B, how is that possible?

In: 23

Answer 1

The plane from B to C might not be full, so the airline wants to sell those tickets so they can get the value out of it by selling those tickets for extremely cheap. The plane from A to B is likely full, but the airline gave you a discount to encourage you to buy the flight from B to C.

This way you get a cheaper flight from A to B.