Most young people (certainly those under the age of eighteen 18 years) have probably never even thought of making a will but they may have underestimated their net worth (or their potential net worth). If a person dies young their estate may be worth a substantial amount because, apart from their obvious assets, the death benefit from their superannuation may include a large amount from an attached insurance policy, their estate may be entitled to workers compensation, or they may just have inherited from an estate of a friend or family member.
There have been many unfortunate incidents of people dying unexpectedly without a will and the lack of a will causes additional stress on grieving families. Generally, when someone dies intestate (that is, without a will), their estate assets will be inherited by their spouse, followed by any children, parents, siblings and so on. This is also specified in the "rules of intestacy". However, the rules of intestacy can sometimes result in brutally unfair outcomes. Also, issues have often arisen when a person dies, and their family have no knowledge that they had a spouse or de facto partner who is entitled to claim part or all of the estate. This can of course be distressing for families and can lead to long and unwanted legal battles.
There are of course many cases where it is appropriate that the young person does not wish to go to the expense of making a will. In order to determine whether a will should be made, you need to consider how the rules of intestacy would apply in your current circumstances. If your estate would be very small and the rules of intestacy will give your assets to appropriate people, then you don't need a will. If on the other hand you would like your gift to go to people other than those that would receive under the rules of intestacy, or if net worth on your death is significant, then it is far better for all concerned that you have a will.