Does TA really work?
Let's re-phrase the question:
Can the markets be profitably exploited by any kind of systematic approach?
Now let's cut directly to the bottom line.
For a system to be successful:
1) return must exceed risk/drawdown, to the point that the exercise is worthwhile, according to one's personal objectives;
AND
2) risk must be managed (e.g. through use of stoplosses and position sizes) to the point that drawdown is never likely to either:
a) compromise total trading capital irretrievably, OR
b) become emotionally intolerable.
Return and risk on each trade are ultimately determined by entry and exit points.
Assuming a TA-based trend-following system of entries and exits, then, in the time frame that one is trading:
a) if prices happen to trend often enough, and far enough, on balance, to overcome both margin for error (i.e. in being unable to enter/exit exactly at peaks and troughs), and transaction costs; AND
b) if one has the discipline (i.e. courage, patience and confidence) to exploit these trends sufficiently;
THEN one will ultimately profit; otherwise one will ultimately lose.
Of the above: (a) lies outside of the trader's control; (b) lies within it.