Until you change this train of thought, you won't succeed. You need to convince yourself before you can convince others. If you can't even convince yourself, no one's going to buy into it.
If you can convince yourself that you have what it takes to succeed and that your secret sauce or magic formula is enough to staff off even the likes of google, then you'll still convincing others including those VCs you've mentioned.
While I agree with you that you need to be an optimist, you also need to be realistic. If you have no track record and start building a company to compete with virgin galactic you will fail.
Ultimately it's about what you want to do with your life; you can reach for the stars, get a nice safe job at a big company or somewhere in between. But you should acknowledge that the more of a risk you take the likelier you are to fail. Most people with highflying dreams don't make it, and you should factor this into the equation.
It's about being a dreamer. It's about being a risk taker. It's about being overconfident in realms that may be familiar. It's about being so passionate about what your doing, it becomes infectious.
Realists are better fit for project managers at large corporations...
No, that's being an idiot.
A successful entrepreneur - as opposed to someone who loses their shirt - may be a visionary and a dreamer. But they take calculated risks. You have to know when to persevere, when to pivot, and when to give up - especially if you're playing with other people's money or your life savings.
Yes, vision and confidence are important, in order to bring employees, investors and customers on board. But unless they are grounded in reality, you will fail horribly, unless you are very, very lucky.
AFAIK having some mild mania helps in this regard. Probably there are also ways to hack your mind to temporary ‘disable’ doubts that can tone you down.
or maybe you just bring a pusher onto the team to spread the word if the hacker is more of a diffident type