Making a Will is not about wealth it is about making sure that what you want to happen to your estate does happen. It gives you the opportunity to specify such things as who will administer your estate, who will care for your children and who will receive specific items of your property.
If you write a best-selling novel you will be entitled to royalties from the publication. These will continue for the period of copyright and may be bequeathed to your heirs.
The most well-known example of this is the rights to Peter Pan which were bequeathed to Great Ormond Street Hospital for Sick Children. Other famous wills include that of Michael Jackson see http://www.forbes.com/fdc/welcome-mjx.shtml.
If you are a really famous author you may well need to appoint separate executors known as literary executors, to deal with royalties from your music or literature.
In that event you almost certainly have a tax problem as well and require expert advice.