Four American college students learned last week that free music downloads can carry a hidden price tag --- US $ 12,000 to $ 17,500, to be exact. Major record companies accused the students of fueling music piracy  by running file-sharing networks on campus allowing hundreds of songs to be downloaded for free. Last Thursday, the four promised not to violate the companies' copyrights. Although they did not admit any wrongdoing, they each agreed to pay thousands of dollars to the Recording Industry Association of America (RIAA). "I don't believe that I did anything wrong," said Daniel Peng at prefix = st1 /PrincetonUniversity, one of the four. "I hope that for the sake of artists, the larger issues can soon be resolved." None appears to have made any money off the file-sharing systems they operated, which were confined to their campus's computer networks. The payments mark the first time record companies have recovered money from individuals in the USaccused of piracy on file-sharing networks. This may be a sign of things to come, as the industry starts taking its battle against online piracy directly to users. Many record-company executives  blame the long slump in CD sales on file-sharing networks, which let users copy songs from each other's computers for free. Matt Oppenheim, senior vice president of business and legal affairs for the RIAA, said the settlements, although well below what the companies could have asked for, were "the right amount" given the situation. He also noted that since the four lawsuits were filed, at least 18 campus file-sharing networks have been taken down by their operators. What's the main idea of the whole passage?
The students should be responsible for their behavior. It's too late for record companies to protect their rights. Record companies have taken action to protect their copyrights by accusing individuals of piracy on file-sharing networks. Some record companies wanted to earn money by accusing people of pirating music.