Because if you believe things are going to go well, then the chances they will are that much bigger!
Every so often, I am reminded of the polytheistic beliefs of ancient Greece, and how that occasionally ended up with “a god for everything”. Not one single god ruling over all that is but rather numerous smaller gods, each with their own niche market, so to speak. We all knows of Zeus, Poseidon, Hades. And they were big players, sure. But let’s be real here, we wouldn’t be anywhere without Verminus, the god that protected cattle from diseases and worms.
In a way it makes sense to have a god for every little thing though. It’s all about having faith in things. Making offerings to Aphrodite, goddess of love, before going on a date with that decorus virgo from next door is sure to give you that extra bit of confidence you need to seem more appealing! And if you offer your oldest cow to Verminus, the disease-prone creature can’t catch and spread any nasties around your herd!
Sadly that doesn’t do away with reckless stupidity. I wonder if they had a god for that.