OBLIGATORY DISCLAIMER: I don't own Criminal Minds, or any of its associated characters, plots, scripts or episodes.
Damaged
There were many reasons why people joined the FBI. While it was possible they were there because they had a genuine wish to help others, generally speaking, if you dug long enough and deep enough, they were all damaged.
The profilers, the BAU were some of the worst. It was the damage to their psyches that helped them to deal with the horrors they saw every day. Pick a member of the primary team and you could generally pick out their 'childhood trauma'.
SSA Rossi, for instance, the death of his son fuelled his first divorce. The second and third were caused by him still being in love with his first wife. There had been a chance that he'd escape, the writing career gave him the opportunity, but at the first chance he had there he was pushing his way back into the unit. Back to the only family he trusted wouldn't desert him.
Morgan and Hotch were the standard childhood abuse cases. Hotchner even admitted the same to an unsub; that there were two ways to go – either grow up to abuse in your turn or to catch the abusers.
Emily Prentiss was a classic victim of parental success. Everything was available to her, all the opportunities to succeed in a career of her choice; after all the world was still steeped in nepotism rather than being the meritocracy the masses tried to convince themselves it should be. Her decisions, her need to be part of the 'it' crowd drove her high school vulnerabilities. The aftermath of that slip driving her first into Interpol and then into hiding in the FBI.
Doctor Reid. The need to collect multiple degrees said something; a level of insecurity around his own intelligence, a need to prove to himself that he was worth the praise that was heaped upon him. Just another victim of the bell curve in reverse.
Then there were the failures. Jason Gideon and Elle Greenaway, these were the ones that shattered. Their issues weren't far enough in the past for the scar tissue to be thick enough to protect them when the bad times came. At best it formed a scab, there to be ripped off when their personal trauma came along.
Their problems weren't small; the brutal invasion into their personal lives was extreme and would break many. But others in the team did survive; taking their pain and using it to make themselves stronger.
In all the team there was just one anomaly.
JJ, the golden girl. The corn-fed mean girl never told of any episode in her past that drove her to work in the job she did. The darkest thing she had ever claimed was working to get an athletic scholarship to escape her small town life but there was nothing that pointed towards her ever having been a victim. No burning need that drove her to leave.
Only time would tell if she would be able to survive in the role of a profiler.