To my opinion it's not so profitable as is used to be but therr are still opportunities for arbitrage trading. Although it's not always easy to spot and catch such chances and you really should be very dedicated to such type of trading to achieve some results. And you have to count of great deal of risk too.
i found that the arbitrage trading tend to be speculative even at the end it seems like a lucky based trading technique. you have seen the chcance is there, the gap is there pretty clear for a while and you decide to start arbitrage but guess nobody know that when you successfully moved the coin, the price move down significantly unexpectedly.
that kind experience happened a lot of times.
at that moment you will think that at the end it alwasys about the lucky factor using this technique to trade.
the price margin of each exchange has a difference with the assumption that a stronger exchange volume has a lower price. the price of each coin between exchanges will never be the same at one time, especially if it changes quickly if the difference reaches above 7%.
the only worst thing is if the transaction traffic is very large because of strong interest from a significant price difference, it requires a longer delivery time. If the asset capital sent over $ 1k will still make a profit, as long as the price does not go down due to the sudden influence of bitcoin.