Well, I'm sure whoever bought it already has at least a few nice cars (and for the same price, this Bat was surely lots tougher to find)
And perhaps the winning bidder simply didn't want to wait the decade or so it would've taken to find each of the individual decal bats in NRMT condition. Plus, it's most likely a one-of-a-kind piece.
I agree the final price was insane... but how do you even put a price on it, given there are no comparable examples?