> It's not insider trading.

One might argue it should fall under a different technical label, but whatever label one uses (A) it stinks of corruption and (B) it's only the tip of the iceberg.

People entrusted with government authority to do work for the public shouldn't be personally profiting from how they decide to wield that authority. Imagine a policeman that arrests people while placing bets about how long that person will be jailed, what they'll be charged with, or whether they'll be convicted.

The objection that "it's unfair, they know something other bettors don't" occurs first not because it's the biggest issue, but because it's easier to prove.

The bigger problem is making improper decisions with their work-powers in order to personally profit, a trust and separation which they've already destroyed by placing the bets in the first place.