For all of those you like to say HODL.

If you wait long enough it will bounce back.

As an example look at the Dow Jones stock index.

If you bought in 1929 just before the downturn you had to HODL for 30 years until the price was back where you bought it

If you bought in 1966 just before the downturn you also had to HODL for 30 years until the price was back where you bought it

Don't believe it? see for yourself: http://www.macrotrends.net/1319/dow-jones-100-year-historical-chart

Are you willing to HODL when the price goes down and risk having to wait 30 years to get back up?