Why do people say file-sharing is illegal?

I can see that maybe the copyright infirngement is illegal, you know by cracking .exe's to bypass security and all, but what so ever is wrong wth file-sharing, why are people saying it is illegal?

I think it is more of a jealousy case, this is the "Big Brothers" coming afetr the big sites and stuff, they are trying to scare people out of using torrents, that is the way I look at it in a nutshell, of course it is alot more complex than that.

Well.... for example : i buy a DVD movie , i crack him and put on a tracker , its like sharing whit others illegal sounds a little big to me

i the idea of file sharing is not illegal its the content that is put in it that is illegal..if i made a home movie and wanted to share it thats not illegal.if i rip a cd that i bought and share it that is illegal

yes, the "idea" of file sharing is not illegal the downloading and cracking and using/playing is the illegal part.