THIS — make it transparent, not try to ban it.
And the transparency must be real-time and MUST include the full dox on beneficial owner of the contract/bet, with steep jailtime for falsification/fronting, etc.. They can even say it is for tax purposes — they win that bet, they should pay income tax (and be able to deduct the costs of their losing bets against that specific income type).
I want to know if a bunch of senators or DOD personnel bet on event X, and I want journalists and OSINT watchers to know it in realtime. That gives everyone information while naturally eliminating most of the advantage of insider trading, since nearly everyone will pile into the same trade and the odds/payoff will come closer to the reality.
Knowing who is making the bets doesn’t prevent mildly corrupt officials from driving the outcome that’s going to win them some cash.
Knowing that high-level DOD official were betting on us invading Iran does us no good if the only reason we invaded Iran was so they could win their long-odds bet. Sure, we can try and shame them, but now they're rich and we're fighting another middle-east war.
I guess we shouldn't do this then. If it doesn't completely solve to problem.