When I think of the dot com bubble which is a true bubble, any investor in it would come out with a loss of say 80%, 90% or even 100%.
Compare to that sort of loss magnitude, a hair cut of 5%, 10% from a bond fund would be great in comparison.
Beside if I don't want to rush out the door along with the other guys and sit tight, the loss I would I incur from a bond fund run would be small if I stay until maturity.