On my machine, the initial state isn't simulated. It only begins simulation when I touch it. At which point, the weight causes the bottom blocks to intersect each other significantly.

For me, bottom blocks stay still while those on the very top fall down.

If I open it, click on the background to activate the physics and just keep the tab open, pretty much all of the blocks that can collapse do eventually collapse.

The Nebraska guy’s block remains surprisingly stable, even when the whole thing above it collapses. Very symbolic.

One more pedantic nitpick: when a block gets wedged between two blocks at an angle, it gets slowly pushed out, although there is a lot of weight resting on the top block. That would be realistic only (maybe) if the blocks were made of ice, but not for other materials...

Coefficient of friction is way too low.

Another reason not to let ice on the internet.

Maybe that's what I'm seeing.