Feasibility of if statements and mechanized friends

Since one and a half months my latest robot has only made 4 purchases. Of those, 75% were a catastrophe:

The jittery stuff is the actual stock movement, the straight drop ending each ownership period is the difference between asking and bidding price. On that good day, the robot bought a x12 Danish bull contract on silver, which gained 3.8% in 5 hours and 15 minutes. Discounting the 3.2% price difference, there is only 0.8% left. I checked the autocorrelation of that instrument compared to a few others where my deals haven't gone too well and noticed an interesting thing:

It's not surprising that silver prices are fairly stable, but it's curious that this is where my soft-coded if statements happened to make a worth-while deal.

From very few datapoints I guess that:

1. The volatile price gap between buy and sell is making leverage instruments hazardous.
2. The big price gap makes it near impossible to make a profit by owning an instrument a few hours.
3. Stable instruments might work better.

So what instruments are stable and have lower price gap? Well stock is and does. D'oh! Back to square one.

I've decided to give machine learning a try. Using backpropagation means not knowing what I'm doing, but I've come to the conclusion that only pattern matching can give a good profit, if I keep using soft-coded if statements I'm only going to manage a slight profit at best. The machines are our friends.