You can also ban 100% of gambling advertising and get 100% of the (dubious, but I'll humour the possibility) 'benefits' of gambling, while removing 90% of the downsides.
I'll be honest as someone who doesn't gamble my perception is the prediction markets are just people with inside information using that to con money out of people. I don't see the value in it.
Well if you think of the point as "winning money" then that really sucks (which I've discussed in prior comments as a big problem for overall participation). If the point is instead to extract and compress information into a simple numerical prediction, then the insider trading is arguably a feature more than a bug.
Not to say it shouldn't be viciously punished, to be clear.
Highly liquid markets are good information compression systems, but existing financial markets tend to be impossible to disaggregate with regard to any discrete event you care about.