Steemit has great potential, no doubt, but Bitcoin has the first mover advantage. It's the defacto standard cryptocurrency.
For trading, Bitcoin is a solid investment, though the rewards won't be significant. At this stage, STEEM is a high risk strategy, but one that may well pay off very, very handsomely. It's worth a risk, I'd say, but I wouldn't get rid of all my Ethers or Bitcoins yet.
RE: Why I am Trading My Bitcoins For Steem