It is still possible, but yea eveyone is right. For arbitrage between exchanges it can be difficult.
Why not do some tests with a small ammount of altcoin and try to do crypto-crypto arbitrage, learning by doing is the best.
Do not forget to add the exchange fees and withdraw fees charged by the exchanges.
So far I have heard much talk about Arbitrage,
but i still have to meet the first person who actually does it and does it successfully.
If there is a successful among you, please PM me,
I cant wait to hear this.
I am afraid that most of heavy traders do not follow this beginners section anymore...