People forget he's also a human being.
Human-ish. I'm going to paint a picture.
I don't know about yours or anyone else's day job here, but for me: I do have deliverables, there is a level of flexibility on those deliverables. Some come weekly, some come monthly. I also have a team of people who can help if things come up or I'm struggling. There are days when I'm inefficient and get nothing done. There are days I start up at 8am, go to the dentist at 10, come back, have lunch, then work until 5 or 6. There's also death marches that are tough to get through, but not usually beyond a couple of months at a time.
If you're a doctor then people come in and see you for an hour or so at a time. You send them on their way. If you're an ER doctor you have shifts and someone will eventually take over for you when you need to go home. The same patient can be dealt with by multiple doctors throughout their time in the hospital. Barring a few renowned surgeons who are one of a handful in the world who can do what they do, even doctors get a relief every now and again. If a doctor quits, another will be hired as we have trained people to do these jobs.
It's the same with garbage collection. The job is very important and must be done, but there will always be someone available to do it.
If this forum was unplugged tomorrow people may be disappointed but ultimately they'd disperse to other media to discuss One Piece online.
...
Now for Oda's reality.
Since July of 1997 you have been producing weekly(ish) chapters of a manga. The manga contains a story that really only you can complete. In the early days you're not super successful just yet so your team of assistants is small. They help you draw landscapes and details while you story-board, add dialogue and draw the characters. Every week that SJ is out you're expected to produce a 14-20 page long chapter that advances the plot. This includes drawing extremely detailed images with backgrounds. This also includes being consistent. You can't draw Nami one way today and another tomorrow (unless you're talking the time skip or something). Details on the characters (Luffy's scar, for instance) have to be consistent in every angle you draw them in. If you don't produce chapters you will be dropped from the magazine. If you don't produce chapters you will be disappointing millions of fans. If you don't produce chapters people will question your health, whether you have what it takes to complete your work, and all the while the majority of these people are reading your work for free, on the internet, never contributing a dime of their own money to your success. Many of these people will go so far as to insult you when you decide you can't push out your typical 15 page chapter this week because you aren't feeling well. Many of those same people will call into work for a belly ache, or complain that their country hasn't standardized a 4-day work week.
Now fast forward a bit more. You're very successful. They're talking about making movies about your work and need you to divert some of your writing time to creative contributions towards the movie production(s). They decide a new way to capture more of an audience would be a live action, so you have to be involved in that. You are expected to show up to just about every manga festival and give some kind of update and acknowledgement to your fans. All the while you're still expected to keep producing chapters and advancing your story.
Now move on a bit more and your live action was a success. What the shit? Those always suck. Now you are strapped in for season 2 which will arguably require even more creative input than season 1. You still work for SJ though, so those guys are still hounding you for weekly chapters, too.
Oh shit. You're in your late 40s. Your eyes are going from staring at pages all day and drawing. You're finding that going on few hours of sleep per night is catching up to you. You still have deadlines but your health is slipping. You've been hunched over daily for the past 30 years (because let's not forget, you also worked as an assistant at one point), so you have chronic back pain, carpal-tunnel, and probably aren't hitting the gym regularly to make up for all the sit-down time. Well, you can just hand off the story to... Wait. There's nobody else. This is your work, and those millions of people are your fans who will be disappointed if they don't get that chapter this week.
When Oda isn't feeling well, he seriously has to weigh the fact that millions of people will be disappointed if he puts his health before a weekly release. He produced more in one year than most of us will produce in our entire lives. Most of us would do nothing but bitch if we had the level of expectation he has on him. He's rich, sure, and that definitely helps him towards his goals of finishing OP, but it's not like he's a Hollywood celebrity living in SoCal. He's still working a rigorous job with high expectations, and he can't just decide he's done as easily as say, Taylor Swift could.
