We should never conflate process with outcome, but this separation is especially hard when it comes to decision making. "Of course the outcome determines whether decision-making was good!"
Actually, that's not the case at all. There is certainly a correlation between "good" decisions and "good" outcomes, but remember that there is a difference between correlation and causation. The more you can separate the decision making process from outcomes and view them independently, the more you open yourself up to greater options than you thought possible. In our evaluations, process vs outcome matters tremendously.
Annie Duke (Thinking in Bets), Carl Richards (The Behavior Gap), and many others discuss this concept. The basic idea is that there is a sound methodology to decision-making that eliminates or mitigates bias, reframes or challenges our assumptions, and evaluates risk in proper ways. These methodologies get you to a "good" decision.
Whether or not your circumstances cooperate is another story. If they do cooperate, it's called good luck. If not, it's bad luck.
You want to be a good decision-maker. You don't want to view a single outcome favorably at the expense of a better future decision. That's why you want to measure the quality of your decisions by the process rather than just whether it turned out OK.
You could have a terrible process for making decisions, yet a lucky favorable outcome might make you believe you're a rock star and cause you to make a subsequent string of terrible decisions with terrible results because your process was flawed.
Alternatively, you could have a very sound process and create a fantastic result, only to have life take a left turn and land you differently than where you wanted. But if you practice a good decision-making process and unlink the process from outcome, you will retain a solid methodology that will serve you favorably over the long term and in many more situations - including those with no left turns at all.
So evaluate BOTH the process you used to come to the decision, as well as the circumstances that led to the outcome itself. The conclusion may not be as simple as "it was great!" or "It sucked!" - it might be a more nuanced conclusion that will increase your performance in the future.