bet on the wrong horse
1. To support a person or thing that ultimately fails. I truly believed our candidate would win this election, but it looks like I bet on the wrong horse. I know you're confident about the success of this product, I'm just worried you might be betting on the wrong horse.
2. To anticipate some future event incorrectly. When I was a kid, I thought by the time I grew up we'd have walking, talking robots doing everything for us. Looks like I bet on the wrong horse.