I believe that in term of how people think, you can devide them into two groups - dogmatists and innovators.
Dogmatist love answers. They are the people who will tell you that there is no money in -enter your goal here-. The love answers because it's keeps them safe, it fertilizes their vision of the world full of impossibles. They love telling you why something can't be done, because it makes life so much easier. Some of them are living in so called learned helplessness, the kind of world you think you have no choice to change, therefore you must only conform. It's actually a waste of time trying to change their mind, because the harder you will push the more they will resist. The only thing you can do is to share you vision with them and resist the temptation to give up when they tell you that your goal is stupid.
Innovators on the other hand love questions. They are the people brave enough to ask you how are you going to make your goal happen. They might mention some obstacles you haven't said and ask you how you want to make it. They are not afraid you could challenge their assumptions and ideas, actually they invite you to do so, because they like change and innovaton. They have an open mind and they know many things impossible were made possible. Innovators love to confront.
We are hard wired to defend ourselves, however if someone has told you his big goal, his idea, why not to reply with :" I'm interested, would you tell me more?". Isn't it much more powerful than an answer?