About how you can lose money on trading bonds, what is clearing and volatility, how taxes are paid and so, and so. The fact is, you certainly could lose money trading stock, and broker certainly can sell your shares without your permission (in my country).

Especially if you are poor. But that is common knowledge. And people losing money on stock exchange, on forex, wherever is nothing interesting or new. Is this predatory behavior? Maybe. Almost no retail investor makes money doing risky trades on stock exchange. That is what those people did.

Edit:spelling