Then all the problems just get moved up a week. Unless you do all elections for the rest of time right now, there's always going to be someone wondering what the result of an election which hasn't happened yet. And a prediction market is a good way to answer those questions.
The other option would be to accept you don't know the outcome of an election till after the election. Sure people will keep asking 'who will win?', but there is no pressing need to answer that question in any other way then counting the votes. I'm serious here, what is it that goes horribly wrong if we don't know the outcome of the elections beforehand?
Stock markets, particularly with respect to stock options, are also prediction markets. Sure you may be right that it is betting for snobs. But there are a bunch of incredibly rich snobs as a result.
Yeah, so? People got rich in all sorts of ways, doesn't necessarily make it a good idea or something we should want as a society. 'Make a few people rich at the expense of a lot of others' doesn't fit my idea of 'useful'.