Quote from xelite777:
A system that is "losing" its edge is a losing system, period. It was never a winning system to begin with, simple as that. Google for "top ten trading systems of all time" for example and see how some purely mechanical trading systems STAY profitable over the years, regardless of market conditions.
Secondly, do not forget that in this topic we are dealing with trading systems with a positive mathematical expectancy.
In roulette, if Red comes up 10 times in a row, the probability of seeing another Red on the 11th spin is still the same. So if you lose $5000 at the roulette table, nothing could prevent you from losing another $5000 just as easily.
But here we are playing a different game, a game that consistently makes you money as you keep playing/trading.
So when you lose the maximum drawdown, the probability of losing even more money become extremely remote, from a mathematical point of view.
Why?
Because by definition a winning system ALWAYS recovers from its average and maximum drawdown and keeps making new equity highs regularly.
So the idea of waiting for that average (or maximum) drawdown BEFORE risking any real money truly makes sense.