Why are people so worried about the bubble bursting?

[charttv]

If you are young then the best advice I could offer is to trade a longer term trend following system and continue to do so until you retire, or even beyond.

Amen to that.

 

[juw177]

Yes, after what happened today, I have a glimpse of what panic can do to a bull run.

If you are young then the best advice I could offer is to trade a longer term trend following system and continue to do so until you retire, or even beyond.

Can anyone elaborate on this? Does this mean jumping onboard the next uptrend when one finishes?