Yeah the omnipotent God bullshit breaks when a rainstorm floods a girls camp and kills a bunch of them. But then they claim the devil did it, or even victim blame in a creepy and fucked up way wondering if they were really pure Christians or not, or if there’s some mysterious upside or lesson.

Fucking-eh, he made every calamity that has befallen man, yet the shits still think it's a "good" plan.

So existence is a net negative in your book? I'm fairly pessimistic but that seems somewhat extreme.

That reason? Kill off every living thing god created.

If God exists, I reckon we are a high school simulation project that he forgot and accidentally left running.

Sure, but the logic reveals literally nothing. I can create an entire Sims world for the sole reason to see if the "turn pink clothing in to green clothing" mod works. Does the fact that their existence had a reason actually mean a damn thing?

No rationale argument works on the irrational. The goal is to plant the seeds of rational thought. To appeal to people who aren't completely gone, yet. The meme works perfectly fine.