You are correct that you need an Edge to be profitable. And you must maintain that edge in all conditions. Unfortunately most traders don't know what an edge is, how to calculate their edge, or even whether they even have an edge. Without an edge, and it has to be > 50% just to break even, so looking at least 55-60% at least! To be ongoing successful look for > 60%!
'So, the question is, do you have an edge? If so, what is it?