That depends on the particular situation involved. In some instances, particularly where damages are low, a person is better off just handling the matter himself/herself. But if the matter is significant, the benefit is that the lawyer knows the law and court rules and how to work them to the best advantage of the client. The lawyer often will be familiar with the judges that will hear the case and how local juries tend to react to certain kinds of cases. The lawyer also knows how to negotiate with the medical providers, etc, to help reduce the bite they take out of any award the client gets in the case. In short, hiring the lawyer gives the person a better chance to win and get a higher damage award than if person tries to litigate the matter on his/her own. The law and court rules can be complex, and I've seen pro se litigants with claims that were actually pretty good end up losing and get nothing because they had no idea of what to do and missed critical things that ended up hurting their case.
But given your member name, I suspect you know all this already since it indicates you are connected with a law firm. So what is it that you truly want to achieve here?