Depends on the circumstances. I would definitely pass up on a flight if I was offered $800 if I'm just going home from college, since I live 15 minutes from the airport here in Wisconsin. The net gain of $500 would be well worth it.
But if it's for the purpose of making it to a wedding, graduation, or etc., then hell no. I have an obligation to be somewhere, which is why I bought a ticket for that flight. The ONLY way I'd consider it is if they guaranteed I could get on a flight later that same day, and that I would be reimbursed.