Yeah, I believe that.  Last night my friend and I went out to a party.  On the bus home, this drunk guy started up with us.  He said a lot of insulting things to me, and then threatened to flash me, at which point I told him off.  Then, he grabs my friend (like a full-on hold), and she can't do anything, so I had to physically pull this guy off her.  And then, he pretends like he's going to grab me, and then at the last second he stops, to fake me out.  Calls me a bitch... continues to mutter incoherently to himself, at which point I was really getting scared.  The bus was so crowded we couldn't move to another spot. 

And on that bus full of people, you know how many people helped us?  Zero.  And then, when Mr. Too Cool For Sobriety finally gets off the bus, this guy (who I thought was unaware of the whole thing because he had his eyes closed and his headphones on) turns to me and says "good thing he got off the bus by himself and the driver didn't have to throw him off."  Like... don't you pretend you're on my side, buddy, if you're just going to play statue until the danger is gone.  Honestly...  Like, I know that's not a representation of all humanity, but OMFG I just wish that whole episode didn't happen.

Once I got home I started panicking over it and I had a nightmare about it.  :\  So, in short, yeah.  People have the capacity to be terrible.