Having seen a couple of these massive sell offs in the year I have been involved, OP is correct.  Today is a great day to buy.  Understandably it is really hard to do so.  It gets depressing and there is almost a fear that sets in in which we think "maybe this isn't going anywhere after all."  Or, "Maybe I should just cut my losses and bail." 

I have felt that way but decided to ride it out.  Having only invested what I could afford to lose 100% off put me in a position to do that and I have absolutely no regrets and realize that days like today are the perfect days to buy.