Most of all the copyright prohibit people's thinking, in other words it make a boundary of creativity. The most important and strong point of the creativity is that it have freedom. You have free to think everything. But now copyright stops everything and our creative mind are going to be dead. This could be a big problem at the future that it didn't help developing human nature.
Also artist can make enough money without copyright. There are so many examples about this. The real fans are giving enough money. They will but CD and going to their concert and it is enough for making money for the artist. Also if you have ability of art than the money will follow you. So It is totally illgical for it do.
At last, creative idea can come out with out on the purpose of profit. For example, Zuckerberg did not make Facebook for money but only for the confiderence of the Havard student. But now it become so famous and makes lots of financial profit. Other things with great development are coming from accident or not important idea. So
So these reasons are why the copyright are not profitable. Artist can make enough money without copyrights and copyrights are only making prohibit people's creativity and idea ultimately human developing. So for all these reasons the movement for copyleft is explain enough and perhaps copyleft could be better than copyright.