The younger person with a family would probably need more life insurance because he has more people who rely on him for financial support.
If you are 68 and have no dependents, there is no one to leave your life insurance to, so you have no need for life insurance.
However, the 30 year old has young children to raise who rely on him for financial support. The death benefit from a life insurance policy can be invested and the interest used to replace his income to help provide for his children for the future.
In this scenario, the 30 year old would have a need for much more life insurance protection than the 68 year old. Here's how you can determine how much life insurance you need.