Given the efficiency of information exchange over the internet regarding btc prices on numerous exchanges, I'd venture to guess that these arbitrages only exist because of market barriers that average investors cannot efficiently surmount.

Example: a few years ago there was a difference of a few hundred dollars between U.S. and Chinese exchanges. But you couldn't really trade on the Chinese exchange unless you were or knew someone who was a Chinese citizen.

I haven't researched it, but my impression is that arbitrage is only indicative of market inneficiency. And a corrolary is that by the time you get into a position to take advantage of significant arbitrage, someone will likely have beaten you to it.

In other words, efficiency is antithetical to arbitrage. I welcome alternative perspectives.