I am not sure why I did not come to the realization sooner, but the process of earning a graduate degree is, in many ways, similar to the initiation process of certain clubs and society (open or secret). (Honourary doctorates are not discussed here.)
Like many clubs and society, one cannot join the ranks of graduate degree holders just by filling out a form. In most cases, if someone wishes to apply for admission to a graduate program, one is required to submit (multiple) reference letters, usually written by someone already holding graduate degrees. This is akin to a club denying membership to anyone without endorsement from any current member. The application is then examined mostly by holders of graduate degrees.
If the application is successful, a candidate is then required to satisfy a number of requirements — passing a set number of courses, writing and defending a thesis. Whether the candidate satisfy the requirements is generally determined by people who are already holders of graduate degrees. If the candidate successfully completes all tasks, a graduate degree is granted to the candidate. This is (somewhat) similar to the rituals all prospective members of a club or society have to perform to prove their worthiness.
Once a candidate satisfactorily completes all the requirements, one is awarded the appropriate degree (by the governing body of the institution granting the award, which consists mostly of holders of graduate degrees). A graduate degree is official awarded to the candidate in an elaborate ceremony. Aside from guests, all those present in the ceremony wear robes signifying their rank (Masters, PhDs, or other doctorates). This is (somewhat) similar to the initiation ceremony held by some clubs or societies. The only thing missing is an oath or pledge. (From what I know, pledges made by medical doctors and lawyers are made at separate ceremonies).
After receiving a graduate degree, one often displays one's membership (in the club of advanced degree holders) with pride (by adding suffix(es) to their business cards, for example), similar to what many members of exclusive clubs and societies do.
I admit the notion of likening the process of working for a graduate degree to the initiation process of clubs sounds rather silly, but this may be one way graduate students cope with the heavy demands of earning their degrees, or their entry to the club of advanced degree holders.