Yeah, anyone can easily modify a file so it doesn't match the blacklisted hash and share it with their friends. Once you start sharing it with millions of peopl

Yeah, anyone can easily modify a file so it doesn't match the blacklisted hash and share it with their friends. Once you start sharing it with millions of people across the internet though, the copyright holder is likely to find out about and issue another DMCA takedown. So this is a system that doesn't prevent small scale sharing, but might be somewhat successful at preventing large scale infringement.