Having a website and what goes on it is very important. Healthy, original (and i stress the original part) content is best. Copying someone else's content is a big NO NO and you can get into trouble in a couple of ways.
What could happen if I copy someone else's content?
Well, the search engines frown upon this practice. They don't even like content spinning which is where you take old content and change the synonyms and grammar to make it look like new content. Google and the other main engines have algorithms that read through the entire web and all of it's content. So when a second site comes along that has some or all of the same content of another, it gets disregarded as not important or tagged as a duplicate. This makes you lose rankings in the search engines, which is not a good thing.
The other way of course is to get in to trouble for plagiarism. No telling where that will go. The original owner could either ask you to change it or they could sue you. Neither sounds good to me.