Fear is so very valuable if you have the strength of spiritual character required to handle it well! One needs to be able to be really vigilant in this very precarious world we live in. One does not want to become a victim of some sort, due to ones carelessness or lack of vigilance. Accidents can so easily happen if one becomes too fearless/careless. There are all sorts of natural disasters that one should be prepared for, if one lives in an area prone to them. Fear, certainly motivates one to be prepared.
We have so many really spiritually messed up characters that one does not want to be victimized by. One needs to be afraid of becoming vulnerable to them, and have ones spiritual radar working well so one can sense when one of them might be approaching and you may be vulnerable to them. One can do a lot to make sure one does not do anything to make oneself vulnerable and has the means to protect oneself from harm.
One can use fear to motivate oneself to do to really hard and difficult spiritual(meditative/mind-body)training(with good diet) required to become strong enough and aware enough spiritually so that one will have the spiritual radar to better sense and deal with all sorts of dangers be they from other humans or from the physical world. Also if one want to succeed a lot in this world it is important to be vigilant in taking advantage of every opportunity and avoid costly mistakes. Fear can help motivate one to have that sort of vigilance. ONE HAS TO LOVE HOW VALUABLE FEAR CAN BE!