stazi said:
if people could accurately predict what would happen, then the market would always be up, and no one would lose any money
If all participants could accurately predict what would happen in the future, you would have a much less volatile market that would hover around an equilibrium. You seem to be forgetting that for someone to win money, another person has to lose money.
Let's say that every market participant is a 100% accurate clairvoyant. This means that everyone would have perfect information in regards to future price and information trends. This would result in profitable trades (almost) never happening (since the clairvoyant on the other side of the trade would not enter a losing trade).
Thus we would only see trades occurring based on individual preferences for particular dividend yields or growth profiles.
If only some individuals were clairvoyants, we would have another situation entirely. This also would not result in a market that was always 'up'.