"One such statistic shows that a negative break thru a 5% stop...

"One such statistic shows that a negative break thru a 5% stop will continue downwards 84% of the time so gambling on the 1:5 is a sure bet to the poor house."
Assume this is correct. It still is insufficient information to base a strategy on.
For that We need the expectation. Probability without expectation is only half the story.

Let say for an example that 84% continue downwards but that the 16% that do not Produce a gain that is 6 times higher on average than what is lost on the 84% .
Negative probability , but a positive expectation.
Probabilities alone mean nothing. You can not assume the payoffs are symmetrical they rarely are.