Among all the qualities listed, I consider this the most important of all. Right from childhood in school, I realized that I didn't really do well with subjects I wasn't passionate about. Same goes with real life adult situations. Zero passion means no zeal to even try to be committed and dedicated to ensure that the idea grows into something very successful. Everything would require some push or force, which is not good motivation for business.
Every entrepreneur will strive more with ideas they have passion for. The passion alone is great motivation to work hard and see it grow.
I agree with you I wonder what distance or how successful something entrepreneurs would have been without their passion for their business. Passion makes one to stay consistent, even when there are too many taxes, unfair charges and unfavorable policies made by the government. The Entrepreneur's passion will keep them going in their business and how they communicate with other people who work with th too.