Many want to join such societies as the Sons or Daughters of the American Revolution (SAR and DAR) or as we have in Texas, Sons or Daughters of the Republic of Texas (SRT and DRT). Each have different requirements but all require proof of every date, name and location given. Some are available online - some only by ordering the documents from a courthouse for example.
Researching your tree can be time consuming. It can also be expensive if you need to subscribe to various genealogical research sites such as ancestry.com. You may not have a clue as to how to even begin.
You've looked for months for that ancestor and it's just a brick wall. You just need help to give you the breakthrough so you can continue with your research.
Those that have been researching for years have found 'out of the box' solutions for locating ancestors, particularly helping with those dead ends.
You may have a family story that you're descended from a famous person and want proof. Or you may want to find the descendants of a famous person to start an organization.
There are other things that can be done: