I am a solo backpacker and while I do not climb, per se, I have done some interesting scrambles and backpacks by myself in remote spots.
My mentality is "the mountain will always be there" and I that I can come back another time if I feel the conditions are outside of my comfort zone. That said- I have also "threaded the needle" a few times- like tagging a summit just before the brunt of a bad winter storm hits the mountain. But my ego is not compromised if I have to back out or if I turn back before I achieve the goal of the exercise. After all- I like what I do and want to continue to do it and not die prematurely.
Fear is a natural and rational emotion. It is the survival instinct alarm going off in your head. Fear is your very good friend. You should listen to your friend and take his/her advise. I think alot of bad situations occur when someone disregarded that screaming voice in their head or got talked out of it by another person.
Panic, on the other hand is seldom to never useful. This is what should be kept in check, not fear.
It is especially through my outdoors experiences that I have come to know myself best. I have confidence in my abilities and I have a good idea where both my strengths and my limits are. I am knowledgeable about my sport. I do my homework and go out prepared. But I also know that I must remain fluid and flexible in my thinking as things do not always go as you plan. Sometimes my creativity to improvise and think on my feet comes into play. And, I enjoy this challenge.
Some people- mostly those that have no experience of backpacking- characterize my behavior as "risky". I say that it is a matter of interpetation. What you consider risky as an outsider, I do not- not as an "insider". But your point is still valid. There are some who do seem to enjoy pulling off some very dangerous stunts. Or not pulling them off. I read about these people in books and on websites like this one.
I say, the worst is to let your life go by without doing at least some of the stuff that makes being alive so profoundly joyful!
The brain's fear centre (the Amygdala) is hard wired to generate the fear response. Much of it we don't need in the modern world because, mostly, the animal threat has gone. The deep seated reason why it's there is so that it keeps us out of harms way to ensure we procreate - self perpetuity of ones genetic line. The hard wiring shows itself as real because, even if we produce offspring and they become independent, the fear response is the same. Kind of spoils what we might otherwise take on after we've served our biological purpose.
The dopamine rush we get after a fear event is to quell the excess adrenalin. The dopamine is the part that gives the ultimate high, not the adrenalin itself - as we so often believe. Though it feels good to be adrenally pumped, the dopamine produces the after-laughing, the wows and elation. And very nice it is too. That's the addiction.
In many circumstances fear degrades mountain or other sporting performance - the shakes, the withdrawal of blood from the extremities to keep the vital core with reserve etc. Being master of ones fear centre can be achieved for the betterment of performance, but that is a entire subject itself.
I do it because I like to be challenged, set goals for myself, keep in shape, and experience life. Reaching big goals is a great feeling. I like the adrenaline rush too. Having been a cop, military, and bomb tech, I guess it just fits into my personallity.