Hard to take, but heads-up pre-flop all-in is just going into an area of probabilities.
Betting 41BB on the Dealer pos. with 46o is just crazy, hoping for SB and BB to fold.
KK is a critical hand to fold in this situation an it has about 80% winning probabilities, too.
But lucky fucker on the Dealer hit the straight with non connecting low cards, honestly he could have hit a full house as well, giving the KK guy a better full with the King on the flop. He was also the biggest stack, so playing his advantages only, not so much the hand value.
How do they say? "That's Poker!"
EDIT: I always liked KK for going all-in pre flop (in the right situation), not so much for calling an all-in with them. AFAIR i lost too often with pocket kings when calling a pre flop all-in...