Sure, but then what if in the several hours before the decision is executed, new information comes in?

Your decision maker is now going to make decisions differently than they would if they hadn’t made the bet, due to the financial incentive. It hopefully won’t be blatant, but they’re going to be more committed to the original decision.

> It's much more effective to make the decision first and the bet second.

What did I say that contradicts this?

> Why almost certainly?

Because I haven't seen any clear reporting with evidence documented down to the level of individual decision-making.

The payout is much higher if you make an unlikely thing happen. "Unlikely things" in politics & warfare are probably highly correlated with irrational or irresponsible decisions.