I've been doing an online MBA part-time for a bit over a year now. My latest subject is Maximising Shareholder Wealth, which is basically about greed and all the things which have screwed up the world economy in my cynical opinion. Anyhow, part of the reading this week has been about Market Efficiency and how the stock exchange should always be perfect as the market reacts immediately to information, and that an average analyst should be no more profitable at selecting a portfolio than a child aiming a dart at the financial pages. All information is known, thus there is no advantage for anyone.
Lots of similarities with Betfair obviously as that's what BF is based on, but the key difference is that new information happens during trading, not while the markets are closed overnight.
In a rush now, I'll expand on that further over the next few days. It's fascinating reading which basically says you'll be far better off on Betfair than the stock market.