I think it's happening every now and then that members here are betting against each other for a particular outcome of a match. It doesn't break any rules, even if the members decide not to pay each other up. You can use escrow to hold the bets until the game is done to help settle the win/lose so there's that. Anyway going back, this can be done, it's just that there isn't a lot of trusting going on these days between the members that aren't as established compared to the old heads here.
In my opinion, if it became a regular practice (even with relatively small amounts) it could help for this section to realize who is to be trusted or not.
Have you ever taken a look at the Collectible Section of the forum? Those who engage there have positive trust and feedback and it may be one of the communities here where the most trusted users interact with one another. It would be positive if something like that happened here, sure it would be more likely someone could end up not paying their debt, but that is exactly what the trust system is for.
I've seen a lot of regular collectibles folks that underdelivered or never delivered goods at all. The thing is, you'll never know who to
fully trust as some people are just trying to build their reputation to hopefully jump on to bigger figures, and that's when they'll disappear.
As time passes, we could have a very clear idea on who to bet with and for how much. It is also unlikely someone who is engaged in a signature campaign would risk to be tagged as a defaulter because of a relatively small bet, and those big enough can always get escrow.
It could be used for small amounts, but I'll be wary in trying to deal with someone with huge bets. That, perhaps, will be something that can be handled by an escrow should this come to fruition (hopefully).
But would not this section need an additional sub-section where people can set their addresses and terms of the bet, as it is usually done in the lending/borrowing section?
It could just be another thread wherein people can stake their 'gambling' address to, similar to the one in the Meta section of this forum. I doubt theymos will ever consider creating a sub-forum dedicated to just this one thing.