The glory comes from being able to serve and protect. However, an agent can have much of that glory stripped away from her if she gets involved in an unsuccessful operation. Unsuccessful operations put people at risk.
For example, a particular botched operation called Operation Fast and Furious (Vin Diesel wasn't involved, as far as we know) allowed guns to be purchased by a Mexican cartel. When the ATF lost track of the traffickers, the guns were lost. One of the guns was later used to kill a Border Patrol Agent. Wow.
The stakes are extremely high, and because they can't predict the result of all of their investigations, agents savor those precious, glorious moments in their work. Those precious moments come in the form of kids being able to play in the streets without the fear of firearm and explosive sales. Fewer guns in criminals' hands means fewer people getting shot.