Your options:
1-Believing something will happen based on bad reasons.
2-Believing something will happen based on good reasons.
3-Not knowing and acknowledging you don't know.
4-Believing something will not happen based on bad reasons.
5-Believing something will not happen based on good reasons.
.
In a one-off, you're right, it doesn't matter. 1 and 2 work just fine.
But as a habit, 1 and 4 are the worse options and will make you wrong MUCH more often. You'll be right sometimes, but they're the poorest method for being right. There's literally no reason to do those options.
So if they're the worst method, why choose them, even in a one-off?