Failing vs fail-fast are different. As already discussed, fail-fast is a technique to try something and adjust/pivot quickly based on initial results. Failing and, dare I include fear of failing, is (IMHO) much worse and probably the #1 reason to get started or progress.
Basically, in the risk/reward equation, you don't even start or continue because of this.
For me, I can't risk my family's well-being on being a dreamer, the risk of failure is to great for those who depend on me. Later on in life, I'm sure I'll take these risks again with much less stress on my shoulders.