You are correct, and I am in the processes of doing exactly that - I've been working on it since January. The system is profitable; very profitable. I have many days with hundreds of dollars of profit, and very few days with losses.
I honestly thought that Btc-arbs was real and doing exactly what I am doing, except that maybe they had started their software development a bit earlier to capture more of the February, March, and April profits. But I know arbitrage orders when I see them, and I never saw the order patterns from them.

And before anyone asks, I am not looking for investors. I have enough of my own money in the system, and I would not want outside investment unless I could purchase insurance to protect the investors. Also, I would insist that investors keep their money and profits once the market hits peak profit - but investors will often often try to invest even more money. The hardest part of managing a profitable investment is not finding investors - the hardest part is convincing them to take their profits. No one wants to go home in the middle of the party, but the investment only has a limited capacity.