As with any investing there's a risk appetite/timescale component to thinking about this stuff. Lots of companies went to zero in the dot-com bubble. Even Amazon was down over 90% between the end of 1999 and late 2001, and took until 2007 to recover to its high. NASDAQ overall took 15 years to return to its March 2000 high. Some incredible returns to be had if you waited it all out, to be sure, but it's hard to know what the interim looks like.