There's risk in everything. Riding a bike to the store or lighting a campfire. We all deal with risk in different ways. The idea of this particular situation is to know when the window of risk is at it's lowest point. Why do people wait so long to purchase a new flat screen T.V.? Risk! There is always the risk that prices will come down and they have, but where is the bottom? The bottom only reveals itself after some time, after prices level out.
If I know that Coke (KO) is selling for $67.00 today but it falls to $15.00, is it a good deal? Is there value there? It depends...if Coke is going out of business, then I wouldn't buy it. But if it's just having a business glitch, it could be a bargain! How do I know if it's a bargain? Research, research and more research. Actually, most great buys are decided upon months in advance of the actual purchase. If I know that Coke is a great buy at $67.00 and it stumbles to $15.00 (because someone found a mouse in their Coke) and I buy it at $15.00 and sell it for $30.00, I just doubled my money because of a "temporary setback". If it goes to $45.00, I tripled my money.
This is what you call a no brainer, and happens every day.
This is how wealth is built. Not on luck, but knowing your game.