...getting anything for free is immoral because it deprives someone from making an excess profit, bringing up game demos, the public domain and anything that its creator gives away for free.
If someone wants to give me something for free and it's something that most others would ask payment for, I'm going to assume that the price is still there, but doesn't mean it's necessarily in cash or currency.
Example: I belong to the Early Reviewers Program on the LibraryThing site. Each month there are publishers who make some books available for free, in exchange for reviews. Most books are e-editions now, rather than physical books that have to be snailmailed. I've received some rather interesting books, and some that were godawful boring. And some of them couldn't be reviewed because I was unable to download the e-copy.
For game demos, they say it's immoral because you don't get to enjoy a sample of something for free without paying for it first. "You don't watch the first ten minutes of a film for free just to see if you like it or not. If you want to try a game, buy it first and if you don't like it, sell it."
Actually, if you go to a movie and decide 10 minutes in that you don't like it and walk out, chances are that you will be at least partially refunded, if you ask nicely.
The gaming site where I get my games offers a 60-90-minute trial, to see if I like a game (and more importantly, if it works on my computer). If I do like it, I'll buy it. If not, I just delete it and write a negative review saying why I didn't like it.
For the public domain, just because something has reached a certain age doesn't mean that someone can no longer make a profit from it, even if the original creator is long dead. Just because someone like Charles Dickens is dead doesn't give people the right to read his works for free. If copies of his works still exist, someone can make a profit from it and by reading a copy for free, you are denying that person from making a profit from selling that work and that's immoral, even if the only copies of it in existence are too expensive for anyone to buy. There is no right to have any work preserved, that's just an excuse.
Thank goodness for Project Gutenberg, and that not everything there is 200 year-old literature anymore. Though if that's your thing, or you like old French novels by Dumas, that's a source (I would have honestly tried reading
The Count of Monte Cristo there in French if my second-hand book dealer hadn't found me an unabridged English translation).
For something where the original creator gives something away for free, they consider that selfish because it deprives someone else from being able to make a profit from their work. If a band or a musician decides to give their music away for free, it deprives a record company and record stores from being able to make a profit from their work. They don't care if the original creators make any money from their own work or not.
Hm. Let's see... today is Saturday. At some point in the next few hours, Fabian Salazar of Wuauquikuna will host a livestream of music and multi-lingual chat for approximately 90 minutes, from somewhere in Poland where his studio is. Some of the fans will donate, most won't. I listen to the music guilt-free, because they are offering it freely. I may not contribute money, but I have done the "like/share/subscribe" thing. Apparently that's helpful. And in the meantime I get relaxing native South American music to keep me company as I'm trying to get through another NaNoWriMo competition.
They also have this idea that if anyone gives away what they've created for free, it means that whatever they've created isn't any good. The only reason to create anything is to make a profit, to give it away means that you know it won't make a profit because it isn't any good. Calling it a passion project or a labour of love are just excuses to make up for a lack of talent, because someone who has talent doesn't create because they want to create, but because they only see it as work to make a profit.
Some authors crack down on fanfic writers who dare to play in their sandbox. Waaay back when, people wondered why George Lucas didn't do that. He reasoned that the fans wrote stories and made fan films out of love for the Star Wars setting and characters, nothing they did would ever be better than the real thing, and it kept the franchise in people's minds until the next official film/book came out.
Shame KJA/BH and the rest of the HLP didn't take that attitude when they eviscerated the Dune setting on Second Life, or issued a C&D to a group of Spanish fans who were making a fan film. None of that could possibly have threatened book sales or interest in official movies, and it would have kept the fans' interest up. But this is not something the HLP can wrap its collective tiny, mercenary brains around.
Star Trek fan films, on the other hand, were getting into a murky territory where some of them were getting as good as some of the TV material. For instance, I'd take Star Trek Continues over DiscoTrek any day. There are a few of the Phase II fanfilms that are really good - much better stories than what's on TV. The people who made these did it with the help of crowdfunding, but they charged nothing for anyone to watch it (of course there were certain levels of donations that got some extras).
Most people who write fanfiction understand that it's illegal to profit from it. They write it and post it on one or more fanfiction sites (ie. fanfiction.net, ArchiveOfOurOwn (AO3), Wattpad, A Teaspoon and an Open Mind, LiveJournal, or many other places. TrekBBS (the Star Trek forum I belong to) has subforums where people can discuss the professional tie-in fiction (that people pay for)
and the fanfiction (that's free for anyone to read). The rule is that you don't discuss fanfiction in the TrekLit forum, and everything's fine.