That being said - one thing stands out, as it often does with this sort of story. There's often a turning point that should make any one of us scratch our heads and learn for the future. This was it for me:
"The Duncans’ ordeal began in November 2017 with an unsolicited fax from a broker promising term loans of as much as $1 million at a cheap rate...The spam fax felt like a gift from God."
That's the moment right there that should scream RED FLAG RED FLAG RED FLAG to everyone. Spam never delivers a gift from the heavens. Never. Never. Never. This is the same sort of thing that 409 scammers bank on -- desperate folks that think they're just the luckiest darn people on earth for happening to get this great deal right at their feet. This is not how the world works.
It goes on...
"Without talking to a lawyer, they did. Why not? Doug thought. They intended to pay the money back on time."
Red Flag #2.
"This would continue for about three months, until they’d repaid $59,960, amounting to an annualized interest rate of more than 350 percent. A small price to pay, Doug figured—soon he’d have all the money he needed in cheaper, longer-term debt."
And again...
I'm not blaming the Duncans here entirely, but this situation was avoidable. I hope everyone here on HN reads this tale and learns from it for your own businesses / life experiences.