What I am about to say may upset some proponents of Elliott Waves, but the plain truth is Elliott Waves used by themselves are allegedly of little value in actual trading. Next, ask the 5 traders to specifically define the number of waves they see on the chart. Use a Trading System, which does not rely exclusively on Elliott Waves and other subjective approaches. However, using Elliott Waves as part of a trading plan in conjunction with another time-tested methodology may work for you. Still another reason traders lose, many follow Time Cycles.
Cycles do in fact exist in the markets.
For example, Live Cattle may have a reliable long term cycle of 9 to 11-months, low to low. The problem is sometimes the cycles may come early or late, or skip a beat entirely. Shortly thereafter, the cycle bottoms and the expected move occurs . . . 4-bars into the NEW cycle, and at a higher price. This forces you out of the market because of the sudden loss, stop being hit, or lack of discipline, etc.