90% of the win ratio does not mean that you can always
make profit. It all depends on how tight the stop loss you
set. It can take one big loss to wipe out all of your
accumulated 9 small wins if the stop loss you set is too
lose. You can reduce the loss by tight setting but in that
case you will not be able to achieve 90% win ratio.
An interesting trading stratege in a stock trading magazine
is that you can get 100% wins as long as you sell only the
winning stocks but keep holding the underwater ones.
Everybody know that it will not make one rich but suffer.