A Little Bit About Human Psychology
If you ever tell a child, "Don't touch this", and you understand children, you probably know very well that, depending on the levels of understanding, intelligence, and/or obedience of that child, the child may eventually touch the forbidden object anyways. That's the nature of children. I have bad news for you - it doesn't go away with just children, but there are a few other elements in the equation that may stick around when people grow up, including "You can't tell me what to do", "But you handed it to me" ("Why are there strings attached?"), and "You don't trust me?"/"I already know the law". I'll get back to this in a moment, but first, I need to tell you something about DA and computers.
The DA Clause
When you joined DA, if you ever read the terms of agreement (which I did), you would have noticed a very broad clause stating something to the effect of "Anything you upload to DA you give us the right to distribute EVERYWHERE WITHOUT PAYING ROYALTIES." i.e. You get nothing, but they get free, unlimited copies of your file. Sure, you can take the image down, but they still are allowed to keep it.
It may be obvious to you that DA needs such permission to show your work around the world, but what you don't realize is that you've just given DA permission to give everyone a copy of your work - FREE. Why? Let me explain how computers work.
How Computers Work
In order to communicate, one computer writes on the file of some other computer. The second computer reads this and interprets it based on the order of the bits (1s and 0s as they are called). These bits are inherently meaningless, and in fact, there are probably programs out there that could reread your entire hard-drive as something else. You could be the biggest "thief" or "pirate" of music and not even know it - simply reinterpret the bits on your computer's hard-drive. There are, in fact, dozens if not hundreds of copies of similar bit sequences of your computer. That's just the way it works. But we have programs that interpret those bits and cause your monitor to project colors that your eyes sense. And your brain says that the result is a "dog" or some familiar image or something, but it all started with inherently meaningless bits.
The way computers communicate says something about how they store data. In order for me to see anything you post online, I have to first download and save a copy of the file on my computer. Browsers do this for us, so people tend to believe falsely that because the file is in your browser, it is somehow magically disconnected from the rest of your computer. No, it isn't. In fact, various artists' works are, as of now, in my browser's folders that are in my program files in my main hard-drive. With a couple clicks, someone could move their files out of the "temp" directory (which, by the way, isn't frequently cleared (files deleted) anyways since browsers want to cache (save) websites for a faster viewing experience), and then they can move those images to their picture folder and enjoy viewing them indefinitely. And notably, if those are DA images, they have merely saved the copy that you legally gave them by agreeing with the aforementioned DA clause.
DA, like other sites, tries to get around their legal involvement by claiming that the artists all reserve their rights to copying, but this holds the weight of a grain of sand in regards to what I just mentioned (EDIT: Let me clarify that: it holds little weight with respect to the right to the act of copying a file off DA (which was made legal in the first clause I mentioned), to say nothing about other areas of copying).
What can you do about it? You may not be able to say, "No, you can't copy this", but you can ask people to not keep it, and for that, I've developed a stamp, which I'll talk about in a second.
In short, at most, all I have advocated for is the fact that people are allowed to download (and save) at least one copy of your work on their computer. It does not entitle them to do more with it - a discussion of that requires a lengthy article of another kind.
A Better Stamp
I go around seeing this "STOP: Copying is Illegal" stamp very frequently. However, this is 1) inherently useless because of what I just said about how computers work and the permissions you gave DA and 2) offends people, in accordance with what I said about human psychology.
Let me dwell on point 2 for a moment. There are two kinds of people: those who are going to save your image, regardless of what your copyright stamps, and those who aren't. The latter you don't need to worry about. These are generally people who understand the hard work of the artist and/or will look at the license on the side bar anyways. The former are the people you want to stop, but here's the thing: You can't get rid of all of them, but you CAN make more enemies.
How do you make more enemies? Simple: Treat them like idiots. People today have had it shoved in their throats time and time again that they aren't allowed to copy (even though that's how the entire present-day digital economy works). The easiest way to tick them off is to be a jerk and make all kinds of remarks about how people are "stealing" your art (another term that is overused and improperly used) and "pirating" etcetera. (Note: I understand some of you are worried for legitimate reasons, such as people posting your works as their own or selling your works without your permission, and you have my sympathies, but that's a different topic). The people who do these things know they aren't "stealing" (in the original sense of the word: "taking something away from the owner"), and the respectful people feel like they are being badgered.
So how do we make/keep friends? Simple: Be polite.
In that regard, I've created a couple of stamps that I think model the idea of politeness and computer-correctness (well, in a general sense):
I think the former is more computer-correct and more specific (assuming I posted it in the correct order, lol), but I'll let you be the judge of that.
Feel free to use these wherever. The license on them says CCC + Share alike, but you don't need to credit me.
Overturned Tables - Rant Section
It is ironic that people who promote copyrights may also be some of the biggest violators of copyright law. A visual artist might turn hypocrite and listen to music on Youtube. They are, in fact, violating copyright law even though they claim "The music never left Youtube". I have already shown why this is wrong, so no one is left with an excuse. Believe it or not, for all the hours some digital artists poor into their work, it actually takes about five to ten times that for making good quality music. Good quality, creative music isn't something you simply sit down and put together in an afternoon or even a couple days. It takes a LONG time. You don't really realize that when you pay $1 on iTunes or Amazon, but you do realize it when you try making it yourself. That said, there needs to be respect for artists in all sectors, not just the area you have an understanding of.