Go directly back to econ 101 and on your way there, read up on the downfall of Barings bank and Nick Leeson. Arbitrage by its very nature is prone to risk and loss.
sorry dude, but that doesn't make you look any better than him, because arbitrage by the book IS indeed riskfree profit, as you just utilize the imbalances between two markets for your own favor. you do this by making two trades: trade a) is buying at market one for price x and trade b) is selling at the same time at market 2 for price x+y, where y is you margin. that is what they are teaching you in econ101

the ypn-google-adsense-dilemma is, that there is no "same time" but instead a probability-function that does include an "lose it all"-outcome

arbitrage by its very nature therefore is risk-free, fucking around with google is not
