A lot of us live our lives according to the expectations of others (our parents, society, etc) because this is all we know how to do at first and what the "system" reinforces through school, career, etc. and this difference between what we want to do and what we actually end up doing can end up causing lots of suffering to ourselves (and to others).

I've seen fear as the primary obstacle to trying something different when the current route is not working. It's really hard to step outside the comfort zone in those situations.

My 2c as someone who has ended up in a non-traditional career track, mostly doing my own thing and getting paid for it.

While you definitely need a higher than average tolerance for uncertainty, the big thing is just not seeing all the options. Many choices are occluded by the options presented to you by employers, the educational system, etc. The spectrum of careers, which is a continuous higher-dimensional blob of "things you can do to make money", is systematized in such a way that while there are paths to unusual career outcomes, most of those paths can not be expressed.

You may on some level want to reach some career or lifestyle goal, but often the path to that destination isn't obvious, and it's definitely never presented to you as an option among the things you can choose, and more than likely you'll have few if any role models or people to ask for guidance if you find yourself on that track.

Not just fear of failure, but fear of disappointing people, losing status, or admitting (to yourself and others) that the plan you’ve been following isn't actually working