It's very cyclical. For reasons unknown to me, pilot unions have always negotiated a seniority-based pay scale. Where seniority is only how many years you been at the airline. How much total experience you have doesn't matter just how many years you've been with the airline.

So if you stay with the airline for a long time you move up from first officer to Captain and then as years of seniority add up you start making a lot more.

The trouble is the pilots can't threaten to change jobs because if you move from one airline to another your seniority goes back to zero.

Also if an airline declares bankruptcy, all the union contracts are null and void. The airline then has a ton of leverage because the pilots are all out of work. The pay scale that comes out of bankruptcy is typically very low.

Similar if one airline acquires another airline. The pilots at the acquired airline typically get screwed in the pay scale and seniority calculation.

Also jobs like flying cargo planes or piloting for a commuter airline pay very low wages. It's mostly just the big airlines that pay well.