So, the denied boarding compensation is capped at $400 plus involuntary refund for all fares above $200...

Suppose that you know long in advance you will really need to fly at a specific time, and buy the ticket at, say, $2000 because of advance purchase fare. If now before the flight anyone wishes to buy a ticket at walk-up fare, say, $2500, then the airline has every incentive to sell the ticket, overbook the flight, and involuntarily bump you. Right? As soon as the price difference between advance purchase ticket and walk-up fare exceeds the denied boarding compensation, you would be liable to find at the airport that all you get would be involuntary boarding compensation and involuntary refund.

Correct?