There are regulations. E.g., in the US, 17 CFR § 40.11 prohibits contracts on "terrorism, assassination, war, gaming, or an activity that is unlawful under any State or Federal law" [0]. The problem is that those responsible for enforcing those regulations are currently uninterested in doing so [1].
If people can threaten journalists for money and get away with it, they will. If people who threaten journalists over money are sent to prison, then after a brief transition period it will mostly stop.
Punishing a corporate entity however is much easier.
We don't seem to have much luck getting it to happen. The larger the corporate entity the more unlikely they'll see any meaningful punishment.
During WW2 when Britain captured all incoming german spies and ran a fake german spy network, they could redirect the german V1 or V2 bombs, by misreporting what they did or didn't hit.
Allowing bets on acts of violence allows the perpetrators to assess their success rate...
There has been an ongoing controversy over the fact that Kalshi (which is subject to US law) chose to comply with the law over the market on Khomeini "leaving office", when the bettors assumed that it wouldn't.