I know what Unit Tests are and the fact is that I use them, they still don't make refactoring easier...
Granted, making sure that everything works afterwards is easy, but I dare you to refactor a large project which usually looks like:
10 Minutes: "Mhhh, okay, I will just change this and ever..."
120 Minutes: "Whoops, well, okay, I see, this depends on this... Uhm, okay, lets change this too and"
180 Minutes: "WTF, why is this method/class used all over the place? Okay, lets change this too"
3 Days: "OMGWTF HAVE I DONE?!!"
2 Weeks: "Can I please discard all the changes I have done and we forget this whole refactoring stuff?"