Or maybe the OP is just realistic? It certainly seems plausible that an established player will have an easier time raising money, generating buzz and getting a product out there than an unproven guy coding at home in a bathrobe.

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.