In that case, you spent $80 to produce an item and exchanged it for $100 worth of their stock.

Now if you check, these companies selling their stock like this tend to have large amounts of debt. If their stock becomes worthless, you just wasted $80 producing an item that their creditors have first dibs on. And liquidating your shares immediately to ensure your gain, would weigh on their stock's value, potentially to the point where their stock would be only $80 worth, and you wouldn't be gaining anything anymore. Your earnings would then tank, alongside them.