Why are flights with layovers in the opposite direction cheaper than direct flights?

Question

Why are flights with layovers in the opposite direction cheaper than direct flights?

In: Economics

Answer 1

If there are only three flights a week between X and Y, but 3000 flights a week between X and A and 3000 between A and Y, then the supply of X-A-Y layover flights is literally a thousand times greater than the supply of direct flights between X and Y.