Another reason is everyone wants to back the next Steve Jobs, and if you don't have those Jobsian traits, you fail the investor pattern-matching test.
Some startup CEOs know this, and have really perfected the VC signaling down to choices of clothing, speaking styles, and shitty treatment of (some) employees.
I heard something similar from an older advisor at the MIT Venture Mentoring Service. He said something to the effect of, "if you're not raring to go" and "your board has to practically hold you back" then investors wouldn't fund you. He was probably right.