First of all, if it's done intentionally, it's fraud. And if two people have blabbed to random Substack guy, then this would be easy to prove.
Secondly, what exactly is the strategy here? Borrow a ton of money to buy buildings, then default on them and walk away? Where's the profit exactly?
Third, the firms capable of raising this level of capital also care about their reputation and ability to borrow money in the future.
And finally, the buildings won't be worthless when the bank takes them over, they'll just be worth less. To lose trillions here, this would have to happen on a scale of $10 trillion or more? The entire commercial real estate market in the US is only worth like $20 trillion.