Wait, so your friend (or acquaintance?), bought an apartment in cash? Or does he regularly makes cash deposits below $10k?

Please clarify because those two things are THREE orders of magnitude apart.

Buying an apartment with a briefcase full of money is something you see only on Disney movies.

Small businesses regularly make $20-30k deposits in cash. That represents the weekly cash revenue of a successful McDonald's franchise. You can slip an extra $1-5k in there, weekly - If you do your accounting "right", it looks like you're moving a little more product than you actually are, and is virtually indistinguishable from real business. See Walter White buying a Car Wash in Breaking Bad. You need a bit of scale: 5 or 10 locations to make it really work, but it does work.

I know, but that's still far from making a $1M+-or-so operation with a bunch of cash.

That's the whole point, you just can't drop that much gray money on something at once.

Purchase a property with AU$150,000 in cash, literally a briefcase full of cash.

So, he’d have handed that money to the vendor.

Wow, amazing. I stand corrected then, but I don't think you could pull that off on this side of the world.

I think you drastically under estimate how much dodgy shit goes on all around us all the time.

There is but a thin veneer of righteousness barely covering a small fraction of the lands.