Struggling with ambition, ego, and risk while trying to start a company

I’m an applied AI scientist at a big healthcare company and want to start my own company. I’m passionate about core AI research, biotech, and applied AI, but I only feel motivated to solve big, unsolved (and often far-fetched) ideas — smaller ones feel beneath me.

I also recognize that I’m a bit too entitled by my job and designation, which makes it harder to step out of my comfort zone. On top of that, I fear the risk of leaving a stable career if my startup fails, it might hurt my chances of getting a similar job. These fears and conflicts make it difficult for me to settle on one idea to pursue. How can I overcome this and move forward? Any advice for someone in my position?