I agree with your post in general, but based on the size of the prize, I’d also guess that this contest is likely covered by prize indemnity insurance. The reason being that it’s possible (although even more unlikely) that there could be more than one winner over the time the contest is scheduled to run. And if there is, the station doesn’t bankrupt itself making good on multiple prizes it didn’t budget for–one premium payment, and they’re covered in the event of one or more winners over the contest period.