A successful nail is one that does it's job by staying in one place for a very long time.
A successful bullet is one that does it's job and then gets out of the way for the next bullet to get in there and do it's job.
A bullet makes a lousy nail. A nail makes a lousy bullet.
Using a bullet when you need a nail is bad. Using a nail when you need a bullet is bad.
Trying to be a nail in the chamber of a rifle is not good. Trying to be a bullet stuck in the wall is not good.
Bullets are useful. Nails are useful. Figure out which one you are, or what your situation requires. Don't get the two mixed up.