Any system will have to take on upside-down risk.
Upside-down risk can be the road to trading ruin for ALL systems.
Can you tell me why it changes at a 70% winning rate? How can you have more risk while you are proving that you have better entry skills then those who have less then70% winning trades?
It sounds like if you have not much accidents as a cardriver your risk to get killed in an accident is much higher??? Having more accidents will save you from getting killed???
Your statement is only true for high rate winners that have high rates because they stay in losers to avoid having lower winning rates. For all the others your statement is complete nonsense. I always use fix stops so I can never get ruined.