low level of self-doubt; that's a typical mind-set for a test pilot
Do you actually know any one real test pilot personally?
I do - one was a flight instructor of mine - and I tell you that this statement is rubbish.
Maybe that individual was self-minded / over-confident. Maybe he wasn't. Maybe he had this as a general attitude or maybe just the last 10 seconds in his life. But that is by far no typical personality for test pilots as such. Just the opposite is true: No major aircraft developer on earth would knowingly employ any air cowboy to mess around with prototype gadgets worth years of development and billions of dollars.
Air cowboy = likely to be unemployed soon. Very simple.