If that guy thinks its worth that much then it probably is. For monetization, i would list a couple of exchanges on it coz alot of exchanges would pay top dollar to get listed on such a premium domain.
Not really. Perceived value =/= actual/intrinsic value. Some people are willing to pay significantly more than market price just because they want it so badly they are willing to pay a mark up, want to beat the bids of competitors by a significant margin so that they scare away the other bidders or because they've been conned.
I don't think either of these are right. If the buyer has a good business idea that can potentially make well over a million dollars in profit given sufficient volume to their website then the domain is a good investment if it is one that would generate enough "natural" traffic that is traffic that doesn't need to be generated via ads.
I wold highly doubt that the domain was purchased as a way to "scare" other bidders away. This is a very ineffective way to bid and can end up being very ineffective.