It is always good to assess risk. Heck, I do this for a living. But there comes a point where you have to just go for it. Richard Branson started Virgin with $200 invested in the concept. Talk about just going for it. He had every reason to fail, but didn't. Why? He went for it. He had the passion to ignore what could happen and just made it happen. We need more business people who overlook the odds and invest in their passion, not the data!
I'm not saying failure can't or won't happen. Even I have had to shut down businesses. You move forward. You keep going. You don't stop or talk yourself out of starting anything. You have to be a man or woman of action or you will never know the taste of success.