I want to be a rockstar just for the extrinsic rewards. Is this a good idea? Please help me decide....?

It always good to dream but it's just a dream. You say that your not a great musician and you don't feel melodies running in your head. May be you could find something related to music and follow through with it. Most rock stars wind up on drugs and eventually die. Only a few make it and most of those are so messed up they don't know where they are half the time. Its not worth the risk. But life goes on! Good Luck!