In the past I have brought up ideas to my wife and received a little less than expected response. Often times I would get upset because she wasn’t supporting me and thinking my ideas were wonderful. Through the years I have learned that bringing up a single idea once or twice warrants that kind of response; I would do the same to her.
If there is something you want, I’m predominantly talking about doing something, accomplishing something, or a business venture, then should be open with your spouse and talk to them often about your idea. You should be thinking about it more and more, as “we become what we think about”. Action most definitely trumps everything, but I would definitely not take to climbing Mount Everest before doing many other climbs.
If your spouse thinks one of your ideas is dumb, then find out things about it. Who are the big players? How did they get their start? How big is that industry? How big was it 10, 20, 50 years ago? What do you need to get started? When would you like to get started? How will your spouse be involved? What scares you about it? What risks are involved and how will you protect/shield your spouse/family from those?