Why do you think Crooks taunts Lennie about the fact that George has gone to town where he may either get hurt, or not return in Of Mice and Men?

In my opinion, Crooks taunts Lennie because he (Crooks) is
a man who is angry about the way that he has been treated by all the other people on the
ranch.  Because he is black, he has been treated badly by everyone and so he wants to
get revenge on someone.

They say that everyone wants to be
above someone in their life.  If you are picked on by everyone, you want at least one
person that you can pick on so you don't feel like a complete loser.  I think this is
why Crooks taunts Lennie.  He senses that Lennie is in some way lower on the "totem
pole" than he is and so he will hurt Lennie to help make himself feel
better.