It doesn’t just “seem” ludicrous.
It IS ludicrous. 
Certainly, but those are natural phenomena, and the influence of the moon on them is scientific and in accordance with the laws of physics.
The same isn’t true of its alleged effects on financial markets.
Let’s not confuse natural and artificially constructed worlds, here.
And it is, by many people who study it objectively.
Sometimes.
But Fibonacci numbers aren’t an example of that. They’re nonsense, too. There’s never been anything more than anecdotal evidence arising from heavy selection-bias for those. In objective, independent tests, they’re proven to be no better than randomly drawn lines, and that has been demonstrated. Repeatedly. 