Over the 7 years from 1993-2000, a portfolio of stocks with ".com" in the name far outperformed every other asset class out there. If you held that portfolio for the 7 years following, from 2000-2007, you would most likely go bankrupt.
The "most likely" in that statement is in the sense that you still need to eat, and so if all you've got are assets that are worth 1/100th of what you paid for them, you're probably pretty deeply in debt in the rest of your finances. In the dot-com boom, it wasn't uncommon for people to mortgage their homes to buy stocks, to quit their day jobs to day-trade stocks, or to owe hundreds of thousands in AMT on stocks that were worth less than the tax bill when it came due, all situations that could and did lead to bankruptcy.
Those companies no longer exist so the stock value==0.