That would likely take much longer to default on a loan or loans and owe 700k worth in deficiency than it took this unfortunate kid to lose the same amount even

That would likely take much longer to default on a loan or loans and owe 700k worth in deficiency than it took this unfortunate kid to lose the same amount even if you were trying, and arguably much harder to find those sketchy mortgage brokers and auto houses than downloading an app and making a few bad trades. A loan on a car or house isn't the same as owing 700k to Robinhood, there's nothing to repossess.