it's an honest question and I think about this all the time. If you can solve the funding issue, I would bet a lot more people will choose the more ambitious projects. What can a spaceship company accomplish with $100k?
Here's the first product of Boeing, which built the bottom stage of the Saturn V:
Elon Musk seems like the counterexample because he started with so much capital and credibility. But he was very obviously thinking steps from the start. Each one risky. Build engine. Build high end car. Buildlower end cars. Maybe then build parts for other manufacturers.
Most big goals are reached in steps. The more difficult and risky the goal the more steps there are and the bigger and riskier they are likely to be but they are still steps.
If your goal is building spaceships you could start by doing something useful with satellites as a step 1. This could be a kickstart-able sized undertaking.
https://www.google.ie/search?q=site:https://www.kickstarter....
Obviously if you are trying to push the boundaries of what a cold start startup can possibly achieve, you are going to find yourself on the difficult-impossible border region but that's the point, isn't it?
If your life's work was geared toward making money for investors someday in case you encounter capital, and you were not going to let a lack of capital keep you from starting your pressing research anyway, a number of decades would be expected to have elapsed before you had the most attractive technology you could offer up for investment into.
For those things that truly require decades before maximum fruition, there is no substitute for decades, just do it.
-Unfortunately, there seems to be far more opportunity out there than ability.... We should remember that good fortune often happens when opportunity meets with preparation.
-Pretty much everything will come to him who hustles while he waits.
--TAEdison
Design a better pump. Build a VTVL hopper. Work on a GPS that will work at high altitude / high acceleration. There's a whole group of new-space companies out there. Solve one of their pain-points.