If someone is a great artist and storyteller they are only wasting their own time and talent by making fan work, in addition to being a thief. If they put the time and effort in they could build their own creative properties and characters and have people love that. But I guess that would be harder, so why put in that effort, right?
I disagree on the case of fanwork done by people who are actual fans. In that case the answer is simple: It's done because fans love the series/characters/world. You want to share it, support it, do something with it, because you love it so much. In my opinion, that in itself is not something bad if it's not done for financial/profit reasons.
If it's just used to get more recognition and cash, then that's another thing, but keep in mind it's not always because of that or because people are 'too lazy'...
I agree with this ENTIRELY.
There is nothing wrong with loving something enough to make fanworks for it, whether you share it with others or not. MANY writers start out writing what could be considered fanfiction (heck, Stephen King himself admitted that some of his first stories in middle school were blatant rip offs of movies, but if he didn't write them he would not be where he is today). Many artists started by drawing their favorite cartoon or movie or book characters when they were kids. It is not a waste of time if you use it to further your own talent, use it as a stepping stone to become better at your craft. Writing that awful Self Insert fic with Doctor Who at age 16 would probably get no one anywhere, but at least it started to get them WRITING, and if they continue to do that then it would allow them to get better at writing, figure out how to make the characters more believable, more 3 dimensional, make the story and plot flow more, and maybe even just improve general grammar. Sometimes they don't want to do anything original because they don't like the idea of it, and sometimes they do it just to entertain themselves or other fans.
It is when you rely SOLELY on your fanworks to gain popularity or attempt to make money off them (or in this case, just using someone else's work for what I can't see being anything other then "hey, here's Mickey Mouse, now chop off his head") that it becomes an issue. If you do nothing but Pokemon fanart and expect that to get you somewhere in the world other than "that person who draws EPIC/AWFUL Pokemon fanart"... then you are sorely mistaken. But by drawing that fanart one could discover that, hey, they REALLY like this art thing, maybe they should try their own original stuff.
And then in time they could end up going to a good art school and becoming an animator for Dreamworks.
Basically, what I mean is fanworks may seem like a waste of time, but they can be a stepping stone to original works. Some people would never get started on original projects without doing fan stuff, while others will never once touch it in the least. Some don't want money or fame or popularity, some just have ideas they want to get out and go for the fun of it, no matter what anyone says. Doing fanwork is JUST as hard, if not harder, than original work. Because you are in control of your original work.
In fanwork, you have to keep as close to canon as humanly possible, or the majority of the fanbase will gut you like a FISH if you share it.
Fanwork, to me, is like that awful poetry I wrote in high school. No one will ever see it, and it will not get me anywhere in life. But it is experience and it can help a creative person grow, whether they wish to pursue it as a career or not, because some people honestly don't want to do that. They would rather simply delve into someone else's pool and share it with others, then potentially have one big one that they can't share at all.
I would rather share a small pool with friends than have a big one to myself, even if I have and do go after both.
It's like saying that you should never try to cook meals you see others doing and try to instead go straight for your own recipes. Some people CAN do that. Others need to learn what everyone else has done and copy them with a bit of their own twist before getting the hang of it.
Or saying that by playing different sports as a kid you wasted all the years you could have been solely focused on one, back when you didn't know which one you liked as much.
Fanworks may mean absolutely nothing in the grand scheme of things, but to some it was the first thing they had. By saying it is a waste of time is like saying all the stories that authors never publish were a waste of their career to some. Not everyone is in it for the fame or money... some rightly do not care. They want to do what they love, no matter what the medium. Sometimes it can be used to further something, others it is nothing more than a hobby to relax with. Like reading. Or playing visual novels. When you do not write or make the games yourselves.
TL;DR: Fanworks can be used to improve one's creative abilities and even some professionals have done it. It can also be nothing but fun entertainment to some. Saying it is not worth it at all is like saying any practice or fun is worth nothing in my mind. But you can disagree with me, I know that with something like this it is impossible to come to a concrete ideal or agreement. *shrug* Agree to disagree and all that.