I think passion helps, but it`s not necessary. I think that it is necessary to believe in what you sell or in what service you perform, but I think the word passion is thrown around way too much. When people use that word, they sound kind of flaky to me. I think success is more attainable if you enjoy what you do, but I think few people are truly "passionate".
I think that having passion doesn`t necessarily mean that someone is out of touch with the realities of their market. You can be passionate about beef, to use your example, and yet realize that a lot of people see it as a health threat. You can abandon that product and move on to fish, OR you can find ways to make beef healthier, or show consumers ways in which beef can be good for them, or segment your market better to target customers who don`t care so much about health and just love beef. Passion can make you more creative so that you can keep doing what you want to be doing.
I think passion can get you through the tough times. That`s why I think people say that passion is necessary.
I hope I am doing this correctly, it is my first post here!
For me the above is the opposite. I started a business out of sheer desperation with nothing but the need to make money and now I am very passionate about what I am doing. I think it was the absolute need to make something succeed that I was driven by and now I can relax a little and enjoy it (I think that is what I am doing!). After reading your post, I do believe I would say I am passionate about what I do, and now, it is this passion to be the best that we can be, and to provide the highest quality products that we can, that drives us on.