Maybe I don't understand the bets because they weren't clearly spelled out. Even if HN markdown was actually what held GDP back from 5% growth, you wouldn't be able to tell.

The government asked for market "on whether or not markdown will raise GDP by 1%". Presumably, they want to know if it gets an additional 1% on top of other growth (which is what? Let's say 2%?).

But there are four possible future outcomes to consider:

1. HN gets markdown, GDP grows 3% or higher

2. HN gets markdown, GDP grows less than 3%

3. HN gets no markdown, GDP grows 3% or higher

4. HN gets no markdown, GDP grows less than 3%

Of these possible outcomes, two will be discarded based on the decision to implement markdown, presumably made based on the betting odds, and then one more will be discarded based on GDP's measured performance over the following year.

Let's structure this as a bet. If you believe markdown is good, then you'll believe P(1)+P(4) > P(2)+P(3).

So you say: "I bet that either HN will get markdown and GDP will grow 3+%, or HN won't get markdown and GDP will grow less than 3%". I don't like markdown so I consider taking the opposing side.

But, I also believe COVID vaccines are going to cause GDP to grow 10% next year, and markdown will have a trivial impact in either direction. So in my opinion, P(1)+P(3) >> P(2)+P(4).

Then in that case I'm mostly betting on whether or not I think markdown is going to get implemented, not whether I think it's going to be beneficial. And if the implementation decision is going to be based on which side bets more money, then that's mostly a popularity contest. I just want to bet alongside whichever side is winning if I think the GDP is going to go up anyway for other reasons.