I was at Amzn early '00s when we lost 95% of our market cap. Later at FB I negotiated a down-round in '09, and then in '12 our stock dropped 50% post-IPO. I was on the board of a public company that went bankrupt (Borders) and a start-up that went under (Hello). Some lessons:
Nervous about joining an early stage startup? Let's talk about risk. There are two types of risk: job risk and career risk. People think they are the same. They aren't. They are very different.