While our own career challenges are not quite to the extreme of leading an actual empire, the question of how much ambition is appropriate is the same. If we do not have the internal drive, then our dreams remain exactly that, dreams. If we push beyond our actual talents and skills, we will frustrate ourselves. Therefore, many people stop short of being all they can be, settling for something they can do well. The potential for personal significance is usually stopped by contentment. Entrepreneurs know well that failure is just an opportunity to try something different, but did you notice that they have failed? We all hate failure; it is embarrassing, and sometimes involves hardship for yourself and your family/employees. Not fun at all.
If we are not bumping into a failure periodically, we are obviously not trying. That may be the secret answer to the question of “are you ambitious enough”. Have you failed recently? If not, you need to try something. Are you frustrated with multiple failures? Then maybe you need to just try something different!