When I was in college, I remember seeing the warnings agains plagiarism and thinking, "Why would you even do that?" You see, with all of the classes I took, real research had to go into almost every project. We were required to have a minimum number of sources, too. Which meant that ninety percent of the work took place off of the page. The idea that ten percent of the work was "too much effort" boggled my mind. With academics, it made sense to do the research, then write my own thoughts (where appropriate since the majority of academia frowns on the author using their own thoughts, anyway), and then cite, cite, cite.
In fiction, half the POINT of writing is to create something new to share with other people. The little stories running around in my head sound like they'd be more enjoyable if more people read them. The stories that have already been published: they're either SO exciting that I want to TALK with other people ABOUT them, or they don't hold my interest enough to bother with them (not a put-down on anyone's writing, it's just that it's all subjective, and I'm not going to put effort into something that didn't move me).
Either way, stealing someone else's story is a waste of time. If I love the story, I want other people to read it so that the creator GETS THEIR DUE! If I don't, then why should I waste my time copying the story?
Certainly not for the money. Even if I churned out five stories in a year by stealing someone else's work, and managed to sell them all for, let's say a year (and not through traditional pub because I'd be more likely to get caught), I wouldn't even come close to making enough money to justify my time. Then, when I got caught (notice I said WHEN not IF), I'd owe someone a TON of money, and I'd lose any audience I'd built, and then I wouldn't be able write anymore.
Not that plagiarism is writing. It's copying. In some cases, literally.
It doesn't make sense on any level, so my advice is: don't do it! It's also illegal.
More than that, it can ruin lives.