In this question: Is there a reason why someone shouldn't buy into a temporarily cheap currency of an otherwise solid economy?
One answer said "You're basically making a bet that the market is wrong".
Another answer said "You're betting against the experts that play the game. Why do you think you're better than they are?"
Another answer said "You are not the smartest kid on the block... smart people have looked at things, and using their risk profiles, have determined what they are willing to risk in terms of their investment in the Ruble, compared to other places. If you disagree with them, then invest now in the Ruble, and bet against those people who generally know the systems better than you".
All these answers make perfect sense. But, they seem to be true for any other investment. For example, there may be a stock which seems promising at the current price. But, there are experts who are much smarter than I am, and if they trade the stock at its current price, then they probably know that it doesn't worth so much as I think it is. The same argument is true for bonds, ETFs, real estate... virtually any other investment.
So, suppose I am not an expert, since I have a full-time job which doesn't leave me any time to read detailed financial reports of stocks and other financial stuff - it seems that the only logical conclusion is that I should stay away from investments entirely.
Is this true?