I hate to break the bad news, but photos that are posted anywhere on the internet are subject to being stolen.I don't like uploading my photos to forums, as it has happened people just " save as " the photo and keep it, and I do not water mark.
In those links on 500px the only way anyone can steal the photo is by screen shot, and that's a lot less likely from happening. And I know watermarks aren't a deterrent to theft, but they are hard to remove so if someone saves the picture no one can say they took the photo.
I've been using 500px for over 2 years, so I am not sure how else, could you clarify for me please? You cannot do " save image as " on that website. It is disabled. Screen shots are really the only way that I have seen for 500px.com