Why should they? If they've got a workable solution and are living a happy life, there's no reason to treat it as a problem.
That is a fair point, though understanding one's sleep patterns through professional evaluation can be valuable even if one plans to continue one's current schedule. A sleep psychologist could provide insights about optimising the chosen schedule, identify potential health considerations, and offer additional tools and strategies. The goal is to have more information to make informed choices about one's health.