It makes sense to ban government officials from betting. It's hard enough to enforce insider trading. With legal betting, it's literally impossible.

Another worrying issue with betting is just how prevalent the last election was in betting markets. In elections won by thousands or even just hundreds of votes, betting markets can skew results where betters vote for someone just purely for the bet and persuade, shill for the person they bet on.

I can imagine betters placing a bet on a candidate and then launching a defamation campaign against the other.