yes it is really illegal. everyone is influenced by what others have done and you are able to use other work for inspiration to crate your own, but you are legally not allowed to use more than a small percentage of any art work, especially if it is the most important part (eg a mall symbol/icon on a very large plain background- you would not be able to take that for your own, especially not to use in any money making venture. Everyone deserves to be paid for their work and if someone lets you use something for nothing think yourself very lucky you didn't have to invest time and money and effort into producing it. I guess you don't know what it is like to have your work stolen from you otherwise you wouldn't be asking suck stupid provocative things. there are things like copyrights and protection of intellectual property laws to help protect us. I guess you have a load of pirate movies too if you can't understand why what you're repeatedly asking is so stupid.