Interesting. I also know a trader who majored in philosophy. He does extremely well. I think I could do well in philosophy because it's something that would keep my interest.
Study math or computer science. Get really good grades and then apply to UBS, GS or Bear Sterns, alternative to Citadel or Timber Hill. Forget about philosophy, its fun to read Gottlieb in your spare time but it wont get you a trading job.
one major money manager w/ a degree in philosophy is Bill Miller of Legg Mason. He has a PhD in philosophy from Johns Hopkins but has a BA in econ from Washington and Lee. I am in no way endorsing a degree in philosophy, math or physics and econ would be my first choice (if I had another chance). Also, take the hardest courses you can and get the best possible grades. Unless you have awesome connections (in the GOOD groups/funds) its your best shot.