A chart can always tell you what happened. It can't necessarily tell you what will happen.
Over time, the successful players learn to recognize familiar patterns formed in charts that tend to produce the same outcomes -- rising prices or declining prices.
Can they be wrong? Of course they can be wrong. Part of successful trading is cutting the losses early.
The Nasdaq's third tier, the AMEX can be just as bad, and last but not least, the OTC, it seems, are financial venues that reward failure.