It seems there are hypothetical scenarios where your taxes could exceed your net worth. If you mine a bitcoin worth $1000, and then it's value falls to $100, you could owe taxes on $1000, and the $900 capital loss would only carry forward to the next year.
This seems insane. If I build 3 chairs I do not include the market price of 3 chairs on that day in my gross income, I sell the chairs and recognize the income generated by the sales.
This is why stores that sell physical goods to a blowout sale at the end of the year.