The trader that waited patiently could have spotted the outbreak of this triangle.
If you would like to trade it or similar patterns like this in the future I would recommend the following.
Wait for the candle that actually breaks out of the pattern.
The stop loss should be fairly tight being over the apex if we have a bearish outbreak.
The target should be equal to the distance measured from the top to the low of the triangle just measured now from the point of the outbreak.
This is shown with the second blue arrow to the right.
The stop loss could already be at brakeven but that depends on the trade management of each individual trader.
Best of PIPS