For one, its not gambling if there is not an element of chance. Gambling is only the case where people dont know who will win the Super Bowl, or whether or not you will draw a blackjack at the casino, etc.

If people have direct control over the event being bet on, to the extent that it is not affected by any element of chance, then its not gambling. Its just people with control over a given situation rigging a game to take money from other people. If you went to the casino and the roulette dealer could bet on the game and control where the ball landed that wouldnt be gambling. Neither are prediction markets in most cases.

That doesnt even get into the issues with ethics and incentivizing people in control to do terrible things (or otherwise act amorally or irrationally) just to make money in the prediction market