In light of all the reasons God gives us to be grateful–as a society, a church, in our families, and on the nitty-gritty of our dinner tables–why do so many grumble? We whine because we want to be God. Here’s a dependable observation from a dubious source, Friedrich Nietzsche.
There is a powerful causal drive within [man]: someone must be to blame for feeling bad…And waxing indignant makes him feel better, too: all poor devils take pleasure in cursing, it gives them a little rush of power. (Twilight of the Idols)
In other words, complaining is the closest we get to being God. We know that we can’t actually control anything but if we complain about it, then we can at least make ourselves feel like we are above the problems. Only those who aren’t trying to be God can thank God for whatever He gives. Otherwise we’ll just be fussy devils.