You should retain a lawyer because the insurance company will not necessarily offer you the money that you deserve and, in some cases, they won’t offer you anything at all. An insurance adjuster can try to find ways to claim that there is no coverage under the policy or that your claimed injuries are not as severe as stated or that they don’t exist at all. Their job is to pay nothing, or as little as possible on every claim and they are trained to do exactly that.
Remember that their top priority is to make sure that the insurance company makes money by paying out as little as possible on each claim. It isn’t fair, but that’s how it works and our job is to make sure that doesn’t happen to you. We have to properly demonstrate that the insured party was at fault and, using medical evidence, that your injuries are real and worthy of compensation.