Think of it this way, if your goal of life is to be an oscar award winner, so you spend all your life and money making a film trying to win the award. You're often broke and starve on the street for your film, but you insist to continue. One day a company want to hire you as a cashier, now you no longer have to worry about your money. But you would no longer have time to work on your film, and must give up your dream to win an oscar award.
Now you have 2 choices, try to pursue your epic goal of life and continue to work on your film, but you have to deal with the obstacle(often starve on the street)
Or give up your dream and get a full time job, and no longer deal with the obstacle?
In real life, some people would pick option 1, sacrifice everything for 1 epic goal. Some of people would pick option 2, easier life but nothing epic.
In FFXI, some people would pick option 1, sacrifice a lot of free time/family time/sleep time/w/e for 1 epic goal in a video game, some people would pick option 2, not to chase after a goal for easier life,
which is don't play FFXI(or play FFXI very casually).
And whoever picked option 1, eventually would have to face a situation: After spending entire life working toward a goal, their goals are accomplished.
So you finally won an oscar award after sacrificed everything you have in your life, and now you're done with this goal. You no longer have to sleep on the street because your movie is done.
In FFXI, if your goal is done, you won't have a reason to keep playing anymore. With obstacles or not. That may be the reason why some ppl don't play anymore.