I started to get interest on arbitrage in cryptocurrencies since last year but I could not start for lack of information but I later started in September and though it is less risky but the profits also is not there. I believe among the trading ways arbitrage is the easiest as you just need to know how to track the difference in price in different exchanges and buy from one and sell for another and takes the difference as profits after less fees.  The one that I have see and do is not easy as you have to take volumes into consideration and also the fees as most time the volume may not be able to cover your orders.