> Also, I ain't conservative, [...]
Then don't argue like one. Rather than making a shallow statement about "how people forgot about the evils of something" and leaving at that, get into more detail about the history. Mention specific events.
> The rest of your post makes no sense.
Can you specify what doesn't? I'd gladly do my best to clarify.
> And you want to argue to me that there's no people in position of power that may want to influence events they can bet on?
No, I'm asking why are there such people? How did they get into such positions? What can be reasonably done to prevent such people from rising into them? From what I've gathered, your point is that the mere existence of prediction markets create enough incentives for well-behaved people to misbehave. My position is that they were never well-behaved.
> There's a reason why we prevent people in sports from betting: it's a matter of incentives.
Sure, we can leave it at that. If we ignore everything else. The problem with sports betting is that it tends to convert the practice from a compention of ability into another form of gambling. This does more than create incentives, it creates a negative feedback loop that undermines the point of the practice. Neither prediction markets nor gambling are about preserving the sanctity of fair play, though. Also, for what's worth, betting about outcomes in sports seems to be legal in the US, just that athletes and other involved are prohibited from betting in their games. If your proposal is to ban people in power from being able to bet and implementing systems to prevent them from doing so, then I suppose we are in agreement. But do note that this is less about incentives, and more about trust (you can trust more that agents won't abuse their role and, if they do, it'll be harder to get away with it).
This segways into main issue with your post. Incentives are highly subjective. For all intents and purposes, they always exist. They are the product of people having goals and desires. The incentive to murder always exists. The reason people generally don't "bend everything" for it is that few will satisfy their goals with that, and even less have it as their goal. For the few that do, there's another tool: disincentives. I don't think I need to explain why murdering someone might result in a terrible outcome for most. For the even fewer that murder as their sole and primary goal, they will bend everything to accomplish it, regardless of incentives/disincentives. Personally, I don't find it even worth discussing. This, perhaps, made it clearer why simply saying "there are incentives to do evil" doesn't cut it. A deeper, more contextual analysis is needed.
Unless you can show there are only criminal uses, or even that there are no set of disincentives we can employ to dissuade potentially bad actors from doing evil, a blanket ban is not warranted, specially when it comes at the cost of a human right.