Entrepreneur

"Just start it and figure out the details later" is a little bit of an anti-pattern. Yes, it is generally better to do SOMETHING than to do nothing, as analysis paralysis is a very real problem, but business owners that completely wing it and don't plan for or manage risks that can be identified in advance are setting themselves up for failure.

I helped a friend get a consulting company off the ground a couple years ago. My official title was VP of Risk Management, and I was also responsible for service delivery (cybersecurity consulting). When he would talk about new ideas for the business, I would think through the logistics of what it would take to do it. He chastised me for being negative on more than one occasion, but I never once told him we couldn't do something or that it was a bad idea. I was always supportive and put in the effort to develop the ideas with him. He interpreted me doing my job and planning out what was going to be necessary to implement his ideas, manage risks, and make us successful as being negative.

I'm not suggesting that this is what is happening in your situation, but we, as entrepreneurs, often focus on what I call the "happy path" where things go as we expect them to. Rather than letting your wife's pragmatism bring you down, try to harness it as part of your idea evaluation and risk management process. Create a list of the risks or problems that she foresees and then think through the likelihood that the each event will happen and try to understand the potential impact to your business plan if it does happen. From there, come up with a mitigation plan for each risk in the list. The mitigation plans don't have to be huge, but putting them in writing will get you to think through them in a way that may help her feel more comfortable with the risks that you are taking. Remember, as your wife, those risks do affect her, too. Hopefully validating and addressing her concerns in a more "formal" way will make her feel better about things.