Wrong. Because of the commission and bid/offer spread. Let's assume you trade a lot and your entries and exits are random. You always trade the same size. In the ideal world the total profit and loss of this trategy is likely to fluctuate around zero for some time. However, because of bid/offer and commission, whether you take trades one way or the other, the equity curve will smoothly go down. So, if making wrong decision is your edge, it actually should be powerful enough to overcome these trade costs. Further, if you trade large enough size, when the account value goes down you will likely scale the trade size down or risk running the account into zero. It is a wise approach if there is a clear edge. However, if the trades are random you may have 5 loosers in a row, and after you scale down, the following 5 winners (of the same number of points) in a row won't bring the value of the account to the original value because although gain (measured in price points) was the same as the loss you traded the winning trades in smaller size.
you will lose whether you follow the guru or fade the guru. why? because you are a loser. its in your psyche. finding a quick approach to winning in the markets is a sure sign of a loser. fortune favours the hand of the diligent. do some work you lazy sob (ps backtesting is also for the birds and is the lazy way out. another reason why most lose on et. misery loves company)
i would think the failure probably lies in money management . im sure there are other reasons, but that one jumps out to me